diff --git a/README.md b/README.md
index 5c8de70..3461466 100644
--- a/README.md
+++ b/README.md
@@ -1,14 +1,12 @@
-Python and Algorithms & Data Structures
-=======================================
+# Python and Algorithms & Data Structures
This repository contains a comprehensive study on Algorithms & Data Structures in Python, including an ["e-book" I wrote](http://mariwahl.us/docs/algorithms_in_python.pdf).
-
-Source Code Structure
----------------------
+---
+## Source Code Structure
src/
@@ -57,10 +55,12 @@ src/
├── sorting
+└── Extra Interview Problems
-Installation
-------------
+----
+## Installation
+
The snippets are designed to be used individually. However, If you want to install all fo the libraries in your [virtualenv](https://coderwall.com/p/8-aeka), do this:
```
@@ -68,22 +68,28 @@ $ pip install -r requirements.txt
```
+----
+## Further Learning
-Further Learning
------------------
-[Check out my lessons in machine learning.] (https://github.com/mariwahl/Machine-Learning-Lessons)
+### My Work:
+
+* [Check out my lessons in machine learning.] (https://github.com/mariwahl/Machine-Learning-Lessons)
-[Check out my lessons in numerical methods.](https://github.com/mariwahl/Numerical-Methods-for-Physics)
+* [Check out my lessons in numerical methods.](https://github.com/mariwahl/Numerical-Methods-for-Physics)
-[Neat Problems in Python and Flask](https://github.com/mariwahl/Neat-Problems-in-Python-and-Flask)
+* [Neat Problems in Python and Flask](https://github.com/mariwahl/Neat-Problems-in-Python-and-Flask)
+
+### Third Party:
+
+* [Interactive Python](http://interactivepython.org/)
+----
+## License
-License
-----------
When making a reference to my work, please use my twitter handle [_b_t_3_](https://twitter.com/_b_t_3_) or my [website](http://bt3gl.github.io/index.html).
diff --git a/src/extra_interview_problems/glassdoor/2014/abstract_strucutres/HashTable.py b/src/extra_interview_problems/abstract_strucutres/HashTable.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/abstract_strucutres/HashTable.py
rename to src/extra_interview_problems/abstract_strucutres/HashTable.py
diff --git a/src/extra_interview_problems/glassdoor/2014/abstract_strucutres/queue_with_stack.py b/src/extra_interview_problems/abstract_strucutres/queue_with_stack.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/abstract_strucutres/queue_with_stack.py
rename to src/extra_interview_problems/abstract_strucutres/queue_with_stack.py
diff --git a/src/extra_interview_problems/glassdoor/2014/abstract_strucutres/stack_with_minumum.py b/src/extra_interview_problems/abstract_strucutres/stack_with_minumum.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/abstract_strucutres/stack_with_minumum.py
rename to src/extra_interview_problems/abstract_strucutres/stack_with_minumum.py
diff --git a/src/extra_interview_problems/glassdoor/2014/advanced/lru_cache.py b/src/extra_interview_problems/advanced/lru_cache.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/advanced/lru_cache.py
rename to src/extra_interview_problems/advanced/lru_cache.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/bitwise.txt b/src/extra_interview_problems/bitwise/bitwise.txt
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/bitwise.txt
rename to src/extra_interview_problems/bitwise/bitwise.txt
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/clear_bits.py b/src/extra_interview_problems/bitwise/clear_bits.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/clear_bits.py
rename to src/extra_interview_problems/bitwise/clear_bits.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/find_bit_len.py b/src/extra_interview_problems/bitwise/find_bit_len.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/find_bit_len.py
rename to src/extra_interview_problems/bitwise/find_bit_len.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/get_bit.py b/src/extra_interview_problems/bitwise/get_bit.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/get_bit.py
rename to src/extra_interview_problems/bitwise/get_bit.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/num_bits_to_convert_2_nums.py b/src/extra_interview_problems/bitwise/num_bits_to_convert_2_nums.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/num_bits_to_convert_2_nums.py
rename to src/extra_interview_problems/bitwise/num_bits_to_convert_2_nums.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/set_bit.py b/src/extra_interview_problems/bitwise/set_bit.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/set_bit.py
rename to src/extra_interview_problems/bitwise/set_bit.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/swap_in_place.py b/src/extra_interview_problems/bitwise/swap_in_place.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/swap_in_place.py
rename to src/extra_interview_problems/bitwise/swap_in_place.py
diff --git a/src/extra_interview_problems/glassdoor/2014/bitwise/update_bit.py b/src/extra_interview_problems/bitwise/update_bit.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/bitwise/update_bit.py
rename to src/extra_interview_problems/bitwise/update_bit.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/max_subarray_stocks.py b/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/max_subarray_stocks.py
deleted file mode 100755
index 61d2957..0000000
--- a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/max_subarray_stocks.py
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/usr/bin/env python
-
-__author__ = "bt3"
-
-
-
-def beating_stock(array):
-
- imin = 0
- i = 1
- deal = [array[i] - array[imin], imin, i]
-
- while i < len(array):
-
- deal_here = array[i] - array[imin]
- if deal_here > deal[0]:
- deal = [deal_here, imin, i]
-
- elif array[i] < array[imin]:
- imin = i
-
- i += 1
-
- return deal[0], array[deal[1]], array[deal[2]]
-
-
-
-if __name__ == '__main__':
- array = [7, 2, 3, 6, 5, 8, 5, 3, 4]
- print(array)
- print("Profit: %d, buying at %d, selling at %d." %(beating_stock(array)))
\ No newline at end of file
diff --git a/src/extra_interview_problems/glassdoor/2014/trees/binary_search_tree.py b/src/extra_interview_problems/glassdoor/2014/trees/binary_search_tree.py
deleted file mode 100755
index f3da045..0000000
--- a/src/extra_interview_problems/glassdoor/2014/trees/binary_search_tree.py
+++ /dev/null
@@ -1,72 +0,0 @@
-#!/usr/bin/python
-
-__author__ = "bt3"
-
-
-from binary_tree import NodeBT, BinaryTree
-
-
-class NodeBST(NodeBT):
-
- def __init__(self, item=None, level=0):
- self.item = item
- self.level = level
- self.left = None
- self.right = None
-
-
- def _addNextNode(self, value, level_here=1):
- new_node = NodeBST(value, level_here)
- if not self.item:
- self.item = new_node
- else:
- if value > self.item:
- self.right = self.right and self.right._addNextNode(value, level_here+1) or new_node
- elif value < self.item:
- self.left = self.left and self.left._addNextNode(value, level_here+1) or new_node
- else:
- print("BSTs do not support repeated items.")
- return self # this is necessary!!!
-
-
-
- def _searchForNode(self, value):
- if self.item == value:
- return self
- elif self.left and value < self.item:
- return self.left._searchForNode(value)
- elif self.right and value > self.item:
- return self.right._searchForNode(value)
- else:
- return False
-
-
-
-class BinarySearchTree(BinaryTree):
-
- def __init__(self):
- self.root = None
-
- def addNode(self, value):
- if not self.root:
- self.root = NodeBST(value)
- else:
- self.root._addNextNode(value)
-
-
-
-
-if __name__ == '__main__':
- bst = BinarySearchTree()
- print "Adding nodes 1 to 10 in the tree..."
- for i in range(1, 10):
- bst.addNode(i)
- print "Is 8 a leaf? ", bst.isLeaf(8)
- print "Whats the level of node 8? ", bst.getNodeLevel(8)
- print "Is node 10 a root? ", bst.isRoot(10)
- print "Is node 1 a root? ", bst.isRoot(1)
- print "Whats the tree height? ", bst.getHeight()
- print "Is this tree BST? ", bst.isBST()
- print "Is this tree balanced? ", bst.isBalanced()
-
-
diff --git a/src/extra_interview_problems/glassdoor/2014/trees/binary_tree.py b/src/extra_interview_problems/glassdoor/2014/trees/binary_tree.py
deleted file mode 100755
index 282a28a..0000000
--- a/src/extra_interview_problems/glassdoor/2014/trees/binary_tree.py
+++ /dev/null
@@ -1,205 +0,0 @@
-#!/usr/bin/python
-
-__author__ = "bt3"
-
-
-
-''' Implementation of a binary tree and its properties. For example, the following bt:
-
- 1 ---> level 0
- 2 3 ---> level 1
- 4 5 ---> level 2
- 6 7 ---> level 3
- 8 9 ---> level 4
-
- has the following properties:
-
- - SIZE OR NUMBER OF NODES: n = 9
- - NUMBER OF BRANCHES OR INTERNAL NODES: b = n-1 = 8
- - VALUE OF ROOT = 1
- - MAX_DEPTH OR HEIGHT: h = 4
- - IS BALANCED? NO
- - IS BST? NO
-'''
-
-
-class NodeBT(object):
- def __init__(self, item=None, level=0):
- self.item = item
- self.level = level
- self.left = None
- self.right = None
-
-
- def __repr__(self):
- return '{}'.format(self.item)
-
-
- def _addNextNode(self, value, level_here=1):
- new_node = NodeBT(value, level_here)
- if not self.item:
- self.item = new_node
- elif not self.left:
- self.left = new_node
- elif not self.right:
- self.right = new_node
- else:
- self.left = self.left._addNextNode(value, level_here+1)
- return self ## this is important, because the node return to the main
-
-
- def _searchForNode(self, value):
- if self.item == value:
- return self
- else:
- found = None
- if self.left:
- found = self.left._searchForNode(value)
- if self.right:
- found = found or self.right._searchForNode(value)
- return found
-
-
- def _isLeaf(self):
- return not self.right and not self.left
-
-
- def _getMaxHeight(self):
- ''' Get the max height at the node, O(n)'''
- levelr, levell = 0, 0
- if self.right:
- levelr = self.right._getMaxHeight() + 1
- if self.left:
- levell = self.left._getMaxHeight() + 1
- return max(levelr, levell)
-
-
- def _getMinHeight(self, level=0):
- ''' Get the min height at the node, O(n)'''
- levelr, levell = -1, -1
- if self.right:
- levelr = self.right._getMinHeight(level +1)
- if self.left:
- levell = self.left._getMinHeight(level +1)
- return min(levelr, levell) + 1
-
-
- def _isBalanced(self):
- ''' Find whether the tree is balanced, by calculating heights first, O(n2) '''
- if self._getMaxHeight() - self._getMinHeight() < 2:
- return False
- else:
- if self._isLeaf():
- return True
- elif self.left and self.right:
- return self.left._isBalanced() and self.right._isBalanced()
- elif not self.left and self.right:
- return self.right._isBalanced()
- elif not self.right and self.left:
- return self.left._isBalanced()
-
- def _isBST(self, mintree=None, maxtree=None):
- ''' Find whether the tree is a BST, inorder '''
- if self.item:
- if not mintree:
- mintree = self.item
- if not maxtree:
- maxtree = self.item
-
- if self._isLeaf():
- return True
- elif self.left:
- if self.left.item < self.item and mintree > self.left.item:
- mintree = self.left.item
- return self.left._isBST(mintree, maxtree)
- else:
- return False
- elif self.right:
- if self.right.item > self.item and maxtree < self.right.item:
- maxtree = self.right.item
- return self.right._isBST(mintree, maxtree)
- else:
- return False
- else:
- print('Tree is empty')
-
-
-
-
-
-
-
-
-class BinaryTree(object):
-
- def __init__(self):
- self.root = None
-
-
- def addNode(self, value):
- if not self.root:
- self.root = NodeBT(value)
- else:
- self.root._addNextNode(value)
-
-
- def isLeaf(self, value):
- node = self.root._searchForNode(value)
- if node:
- return node._isLeaf()
- else:
- print "Node not found."
-
-
- def getNodeLevel(self, item):
- node = self.root._searchForNode(item)
- if node:
- return node.level
- else:
- print('Node not found')
-
-
- def isRoot(self, value):
- return self.root.item == value
-
-
- def getHeight(self):
- return self.root._getMaxHeight()
-
-
- def isBalanced(self):
- return self.root._isBalanced()
-
-
- def isBST(self):
- return self.root._isBST()
-
-
- def preorder(self):
- current = self.root
- nodes, stack = [], []
- while stack or current:
- if current:
- nodes.append(current.item) # thats what change
- stack.append(current)
- current = current.left
- else:
- current = stack.pop()
- current = current.right
- return nodes
-
-
-
-if __name__ == '__main__':
- bt = BinaryTree()
- print "Adding nodes 1 to 10 in the tree..."
- for i in range(1, 10):
- bt.addNode(i)
- print "Is 8 a leaf? ", bt.isLeaf(8)
- print "Whats the level of node 8? ", bt.getNodeLevel(8)
- print "Is node 10 a root? ", bt.isRoot(10)
- print "Is node 1 a root? ", bt.isRoot(1)
- print "Whats the tree height? ", bt.getHeight()
- print "Is this tree BST? ", bt.isBST()
- print "Is this tree balanced? ", bt.isBalanced()
- print (bt.preorder())
diff --git a/src/extra_interview_problems/glassdoor/2014/trees/check_whether_bst.py b/src/extra_interview_problems/glassdoor/2014/trees/check_whether_bst.py
deleted file mode 100755
index 7bc3eac..0000000
--- a/src/extra_interview_problems/glassdoor/2014/trees/check_whether_bst.py
+++ /dev/null
@@ -1,64 +0,0 @@
-__author__ = "bt3"
-
-
-""" need to keep track of min and max!!!"""
-
-from binary_tree import BinaryTree, NodeBT
-from binary_search_tree import BinarySearchTree, NodeBST
-
-## my solution
-
-def isBST(bt, mintree=None, maxtree=None):
- if not bt.item:
- return True
-
- if not mintree:
- mintree = bt.item
-
- if not maxtree:
- maxtree = bt.item
-
- left, right = False, False
-
- if bt.left:
- if bt.left.item > bt.item and bt.left.item < mintree:
- return False
- else:
- mintree = bt.left.item
- left = isBST(bt.left, mintree, maxtree)
- else:
- left = True
- if bt.right:
- if bt.right.item < bt.item and bt.right.item > maxtree:
- return False
- else:
- maxtree = bt.right.item
- right = isBST(bt.right, mintree, maxtree)
- else:
- right = True
-
- return left and right
-
-
-
-
-
-
-
-
-
-if __name__ == '__main__':
- bt = BinaryTree()
- print "Adding nodes 1 to 10 in the tree..."
- for i in range(1, 10):
- bt.addNode(i)
-
- print(isBST(bt.root))
-
- bst = BinarySearchTree()
- print "Adding nodes 1 to 10 in the tree..."
- for i in range(1, 10):
- bst.addNode(i)
-
- print(isBST(bst.root))
- print(bst.isBST())
diff --git a/src/extra_interview_problems/glassdoor/2014/trees/lowest_common_ancestor.py b/src/extra_interview_problems/glassdoor/2014/trees/lowest_common_ancestor.py
deleted file mode 100755
index bf5f0f2..0000000
--- a/src/extra_interview_problems/glassdoor/2014/trees/lowest_common_ancestor.py
+++ /dev/null
@@ -1,47 +0,0 @@
-#!/usr/bin/python
-
-__author__ = "bt3"
-
-
-from binary_tree import BinaryTree
-
-
-def inorder(node, path=None):
- if node:
- path = path or []
- path.append(node.item)
- inorder(node.left, path)
- inorder(node.right, path)
- return path
-
-
-
-def lowest_commom_ancestor(node, node1, node2):
- path = inorder(node.root)
- i1, i2 = 0, 0
- for i,n in enumerate(path):
- if n == node1:
- i1 = i
- if n == node2:
- i2 = i
- return path[i1:i2+1]
-
-
-
-
-
-
-if __name__ == '__main__':
- bt = BinaryTree()
- l = [10, 6, 14, 3, 7, 11, 15]
- for i in l:
- bt.addNode(i)
-
- print(l)
- print(lowest_commom_ancestor(bt, 10, 6))
- print(lowest_commom_ancestor(bt, 10, 14))
- print(lowest_commom_ancestor(bt, 10, 3))
- print(lowest_commom_ancestor(bt, 10, 7))
- print(lowest_commom_ancestor(bt, 10, 11))
- print(lowest_commom_ancestor(bt, 10, 15))
-
diff --git a/src/extra_interview_problems/glassdoor/2014/trees/transversal_BST_ancestor.py b/src/extra_interview_problems/glassdoor/2014/trees/transversal_BST_ancestor.py
deleted file mode 100755
index 75de17f..0000000
--- a/src/extra_interview_problems/glassdoor/2014/trees/transversal_BST_ancestor.py
+++ /dev/null
@@ -1,44 +0,0 @@
-#!/usr/bin/python
-
-__author__ = "bt3"
-
-
-''' find the lowest ancestor in a BST '''
-
-from transversal_BST_recursively import BSTwithTransversalRecursively
-
-
-
-def find_ancestor(path, low_value, high_value):
- while path:
- current_value = path[0]
- if current_value < low_value:
- try:
- path = path[2:]
- except:
- return current_value
- elif current_value > high_value:
- try:
- path = path[1:]
- except:
- return current_value
- elif low_value <= current_value <= high_value:
- return current_value
- else:
- return None # this is probably never touched
-
-
-
-
-if __name__ == '__main__':
- bst = BSTwithTransversalRecursively()
- l = [10, 5, 15, 1, 6, 11, 50]
- for i in l:
- bst.addNode(i)
- path = bst.preorder()
- print("The path inorder: ", path)
-
- print("The path between 1 and 6 is :", find_ancestor(path, 1, 6))
- print("The path between 1 and 11 is: ", find_ancestor(path, 1, 11))
- print("The path between 11 and 50 is: ", find_ancestor(path, 11, 50))
- print("The path between 5 and 15 is: ", find_ancestor(path, 5, 15))
diff --git a/src/extra_interview_problems/glassdoor/2015/check_if_bst.py b/src/extra_interview_problems/glassdoor/2015/check_if_bst.py
deleted file mode 100644
index e9da054..0000000
--- a/src/extra_interview_problems/glassdoor/2015/check_if_bst.py
+++ /dev/null
@@ -1,56 +0,0 @@
-#!/usr/bin/env python
-
-__author__ = "bt3"
-
-
-'''
-Given a tree find out whether is a BST or not
-'''
-
-class Tree(object):
- def __init__(self, value):
- self.value = value
- self.right = None
- self.left = None
-
-def create_tree_bst():
- tree = Tree(4)
- tree.right = Tree(6)
- tree.left = Tree(2)
- tree.right.left = Tree(5)
- tree.right.right = Tree(7)
- tree.left.left = Tree(1)
- tree.left.right = Tree(3)
- return tree
-
-def create_tree_not_bst():
- tree = Tree(4)
- tree.right = Tree(6)
- tree.left = Tree(2)
- tree.right.left = Tree(5)
- tree.right.right = Tree(7)
- tree.left.left = Tree(3)
- tree.left.right = Tree(1)
- return tree
-
-
-INFINITY = float("infinity")
-NEG_INFINITY = float("-infinity")
-
-def isBST(tree, minVal=NEG_INFINITY, maxVal=INFINITY):
- if not tree:
- return True
-
- if not minVal <= tree.value <= maxVal:
- return False
-
- return isBST(tree.left, minVal, tree.value) and \
- isBST(tree.right, tree.value, maxVal)
-
-
-if __name__ == '__main__':
- tree = create_tree_bst()
- print isBST(tree)
-
- tree = create_tree_not_bst()
- print isBST(tree)
diff --git a/src/extra_interview_problems/glassdoor/2015/alpha_permutation.py b/src/extra_interview_problems/math_arrays_and_strings/alpha_permutation.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/alpha_permutation.py
rename to src/extra_interview_problems/math_arrays_and_strings/alpha_permutation.py
diff --git a/src/extra_interview_problems/glassdoor/2015/anagram.py b/src/extra_interview_problems/math_arrays_and_strings/anagram.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/anagram.py
rename to src/extra_interview_problems/math_arrays_and_strings/anagram.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/anagrams_hash_table.txt b/src/extra_interview_problems/math_arrays_and_strings/anagrams_hash_table.txt
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/anagrams_hash_table.txt
rename to src/extra_interview_problems/math_arrays_and_strings/anagrams_hash_table.txt
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/balance.txt b/src/extra_interview_problems/math_arrays_and_strings/balance.txt
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/balance.txt
rename to src/extra_interview_problems/math_arrays_and_strings/balance.txt
diff --git a/src/extra_interview_problems/math_arrays_and_strings/balance_symbols.py b/src/extra_interview_problems/math_arrays_and_strings/balance_symbols.py
new file mode 100644
index 0000000..ff65f82
--- /dev/null
+++ b/src/extra_interview_problems/math_arrays_and_strings/balance_symbols.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+'''
+Given a N different open and close braces in a string "( { [ } ] )".
+How do you check whether the string has matching braces.
+'''
+
+from collections import Counter
+def check_if_balance(string):
+ '''
+ >>> check_if_balance('{[[(])}]')
+ True
+ >>> check_if_balance('{[[()}]')
+ False
+ >>> check_if_balance('')
+ True
+ '''
+ table = Counter()
+ for i in string:
+
+ index = str(ord(i))[0]
+ if i in '{[(':
+ table[index] += 1
+
+ elif i in ')}]':
+ table[index] -= 1
+
+ for i in table.values():
+ if i !=-0:
+ return False
+ return True
+
+
+
+if __name__ == '__main__':
+ import doctest
+ doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/check_2_numbers_array_sum.py b/src/extra_interview_problems/math_arrays_and_strings/check_2_numbers_array_sum.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/check_2_numbers_array_sum.py
rename to src/extra_interview_problems/math_arrays_and_strings/check_2_numbers_array_sum.py
diff --git a/src/extra_interview_problems/glassdoor/2015/check_if_3_numbers_sum_to_zero.py b/src/extra_interview_problems/math_arrays_and_strings/check_if_3_numbers_sum_to_zero.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/check_if_3_numbers_sum_to_zero.py
rename to src/extra_interview_problems/math_arrays_and_strings/check_if_3_numbers_sum_to_zero.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/check_if_anagrams.py b/src/extra_interview_problems/math_arrays_and_strings/check_if_anagrams.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/check_if_anagrams.py
rename to src/extra_interview_problems/math_arrays_and_strings/check_if_anagrams.py
diff --git a/src/extra_interview_problems/glassdoor/2015/check_if_palindrome.py b/src/extra_interview_problems/math_arrays_and_strings/check_if_palindrome.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/check_if_palindrome.py
rename to src/extra_interview_problems/math_arrays_and_strings/check_if_palindrome.py
diff --git a/src/extra_interview_problems/glassdoor/2015/check_non_overlapping_intervals.py b/src/extra_interview_problems/math_arrays_and_strings/check_non_overlapping_intervals.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/check_non_overlapping_intervals.py
rename to src/extra_interview_problems/math_arrays_and_strings/check_non_overlapping_intervals.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/combinations.py b/src/extra_interview_problems/math_arrays_and_strings/combinations.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/combinations.py
rename to src/extra_interview_problems/math_arrays_and_strings/combinations.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/delete_duplicate_char_str.py b/src/extra_interview_problems/math_arrays_and_strings/delete_duplicate_char_str.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/delete_duplicate_char_str.py
rename to src/extra_interview_problems/math_arrays_and_strings/delete_duplicate_char_str.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/fibonacci.py b/src/extra_interview_problems/math_arrays_and_strings/fibonacci.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/fibonacci.py
rename to src/extra_interview_problems/math_arrays_and_strings/fibonacci.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_if_is_substr.py b/src/extra_interview_problems/math_arrays_and_strings/find_if_is_substr.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_if_is_substr.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_if_is_substr.py
diff --git a/src/extra_interview_problems/glassdoor/2015/find_if_numbers_sum_to_k.py b/src/extra_interview_problems/math_arrays_and_strings/find_if_numbers_sum_to_k.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/find_if_numbers_sum_to_k.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_if_numbers_sum_to_k.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_if_unique_char.py b/src/extra_interview_problems/math_arrays_and_strings/find_if_unique_char.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_if_unique_char.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_if_unique_char.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_largest_sum.py b/src/extra_interview_problems/math_arrays_and_strings/find_largest_sum.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_largest_sum.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_largest_sum.py
diff --git a/src/extra_interview_problems/glassdoor/2015/find_longest_str_unique_chars.py b/src/extra_interview_problems/math_arrays_and_strings/find_longest_str_unique_chars.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/find_longest_str_unique_chars.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_longest_str_unique_chars.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_non_repeating_number.py b/src/extra_interview_problems/math_arrays_and_strings/find_non_repeating_number.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/find_non_repeating_number.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_non_repeating_number.py
diff --git a/src/extra_interview_problems/glassdoor/2015/find_nth_fibonacci.py b/src/extra_interview_problems/math_arrays_and_strings/find_nth_fibonacci.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/find_nth_fibonacci.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_nth_fibonacci.py
diff --git a/src/extra_interview_problems/glassdoor/2015/find_prime_factors.py b/src/extra_interview_problems/math_arrays_and_strings/find_prime_factors.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/find_prime_factors.py
rename to src/extra_interview_problems/math_arrays_and_strings/find_prime_factors.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/finding_gcd.py b/src/extra_interview_problems/math_arrays_and_strings/finding_gcd.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/finding_gcd.py
rename to src/extra_interview_problems/math_arrays_and_strings/finding_gcd.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/finding_if_prime.py b/src/extra_interview_problems/math_arrays_and_strings/finding_if_prime.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/finding_if_prime.py
rename to src/extra_interview_problems/math_arrays_and_strings/finding_if_prime.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/generate_prime.py b/src/extra_interview_problems/math_arrays_and_strings/generate_prime.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/generate_prime.py
rename to src/extra_interview_problems/math_arrays_and_strings/generate_prime.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/get_float_rep_bin.py b/src/extra_interview_problems/math_arrays_and_strings/get_float_rep_bin.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/get_float_rep_bin.py
rename to src/extra_interview_problems/math_arrays_and_strings/get_float_rep_bin.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/interserction_two_arrays.py b/src/extra_interview_problems/math_arrays_and_strings/interserction_two_arrays.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/interserction_two_arrays.py
rename to src/extra_interview_problems/math_arrays_and_strings/interserction_two_arrays.py
diff --git a/src/extra_interview_problems/glassdoor/2015/longest_common_prefix.py b/src/extra_interview_problems/math_arrays_and_strings/longest_common_prefix.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/longest_common_prefix.py
rename to src/extra_interview_problems/math_arrays_and_strings/longest_common_prefix.py
diff --git a/src/extra_interview_problems/math_arrays_and_strings/max_subarray_stocks.py b/src/extra_interview_problems/math_arrays_and_strings/max_subarray_stocks.py
new file mode 100755
index 0000000..e6f5f41
--- /dev/null
+++ b/src/extra_interview_problems/math_arrays_and_strings/max_subarray_stocks.py
@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+
+def beating_stock(array):
+
+ imin = 0
+
+ # first deal is just buying in the next day (1)
+ deal = [array[1] - array[imin], imin, 1]
+
+ for i, d in enumerate(array):
+
+ deal_here = d - array[imin]
+
+ if deal_here > deal[0]:
+ deal = [deal_here, imin, i]
+
+ elif d < array[imin]:
+ imin = i
+
+ return deal[0], array[deal[1]], array[deal[2]]
+
+if __name__ == '__main__':
+ array = [7, 2, 3, 6, 5, 8, 5, 3, 4]
+ deal = beating_stock(array)
+ print("Profit: %d, buying at %d, selling at %d." %(deal[0], deal[1], deal[2]))
\ No newline at end of file
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/number_of_zeros_factorial.txt b/src/extra_interview_problems/math_arrays_and_strings/number_of_zeros_factorial.txt
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/number_of_zeros_factorial.txt
rename to src/extra_interview_problems/math_arrays_and_strings/number_of_zeros_factorial.txt
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/permutations.py b/src/extra_interview_problems/math_arrays_and_strings/permutations.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/permutations.py
rename to src/extra_interview_problems/math_arrays_and_strings/permutations.py
diff --git a/src/extra_interview_problems/glassdoor/2015/permutations.py b/src/extra_interview_problems/math_arrays_and_strings/permutations2.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/permutations.py
rename to src/extra_interview_problems/math_arrays_and_strings/permutations2.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/prod_other_ints.py b/src/extra_interview_problems/math_arrays_and_strings/prod_other_ints.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/prod_other_ints.py
rename to src/extra_interview_problems/math_arrays_and_strings/prod_other_ints.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/ransom_note.py b/src/extra_interview_problems/math_arrays_and_strings/ransom_note.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/ransom_note.py
rename to src/extra_interview_problems/math_arrays_and_strings/ransom_note.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/rev_string.py b/src/extra_interview_problems/math_arrays_and_strings/rev_string.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/rev_string.py
rename to src/extra_interview_problems/math_arrays_and_strings/rev_string.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/reverse_words.py b/src/extra_interview_problems/math_arrays_and_strings/reverse_words.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/reverse_words.py
rename to src/extra_interview_problems/math_arrays_and_strings/reverse_words.py
diff --git a/src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/reverse_words_sentence.py b/src/extra_interview_problems/math_arrays_and_strings/reverse_words_sentence.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/reverse_words_sentence.py
rename to src/extra_interview_problems/math_arrays_and_strings/reverse_words_sentence.py
diff --git a/src/extra_interview_problems/glassdoor/2015/sum_two_numbers_as_strings.py b/src/extra_interview_problems/math_arrays_and_strings/sum_two_numbers_as_strings.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/sum_two_numbers_as_strings.py
rename to src/extra_interview_problems/math_arrays_and_strings/sum_two_numbers_as_strings.py
diff --git a/src/extra_interview_problems/glassdoor/2015/binary_search.py b/src/extra_interview_problems/sorting_and_searching/binary_search.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/binary_search.py
rename to src/extra_interview_problems/sorting_and_searching/binary_search.py
diff --git a/src/extra_interview_problems/glassdoor/2015/merge_and_sort_two_arrays.py b/src/extra_interview_problems/sorting_and_searching/merge_and_sort_two_arrays.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/merge_and_sort_two_arrays.py
rename to src/extra_interview_problems/sorting_and_searching/merge_and_sort_two_arrays.py
diff --git a/src/extra_interview_problems/glassdoor/2014/sorting_and_searching/quick_sort.py b/src/extra_interview_problems/sorting_and_searching/quick_sort.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2014/sorting_and_searching/quick_sort.py
rename to src/extra_interview_problems/sorting_and_searching/quick_sort.py
diff --git a/src/extra_interview_problems/trees/binary_search_tree.py b/src/extra_interview_problems/trees/binary_search_tree.py
new file mode 100755
index 0000000..7fcc738
--- /dev/null
+++ b/src/extra_interview_problems/trees/binary_search_tree.py
@@ -0,0 +1,103 @@
+#!/usr/bin/python
+
+__author__ = "bt3"
+
+
+class Node(object):
+
+ def __init__(self, item=None,):
+
+ self.item = item
+ self.left = None
+ self.right = None
+
+ def __repr__(self):
+ return '{}'.format(self.item)
+
+
+ def _add(self, value):
+ new_node = Node(value)
+
+ if not self.item:
+ self.item = new_node
+
+ else:
+ if value > self.item:
+ self.right = self.right and self.right._add(value) or new_node
+ elif value < self.item:
+ self.left = self.left and self.left._add(value) or new_node
+ else:
+ print("BSTs do not support repeated items.")
+
+ return self # this is necessary!!!
+
+
+ def _search(self, value):
+ if self.item == value:
+ return True # or self
+
+ elif self.left and value < self.item:
+ return self.left._search(value)
+
+ elif self.right and value > self.item:
+ return self.right._search(value)
+
+ else:
+ return False
+
+
+ def _isLeaf(self):
+ return not self.right and not self.left
+
+
+ def _printPreorder(self):
+ print self.item
+
+ if self.left:
+ return self.left._printPreorder()
+
+ if self.right:
+ return self.right._printPreorder()
+
+
+
+class BST(object):
+
+ def __init__(self):
+ self.root = None
+
+ def add(self, value):
+ if not self.root:
+ self.root = Node(value)
+ else:
+ self.root._add(value)
+
+ def printPreorder(self):
+ if self.root:
+ self.root._printPreorder()
+
+ def search(self, value):
+ if self.root:
+ return self.root._search(value)
+
+
+
+if __name__ == '__main__':
+
+ bst = BST()
+ print "Adding nodes 1 to 10 in the tree..."
+ for i in range(1, 11):
+ bst.add(i)
+
+ print
+ print "Searching for nodes 16 and 6"
+ print bst.search(16)
+ print bst.search(6)
+
+ print
+ print "Printing preorder..."
+ bst.printPreorder()
+
+
+
+
diff --git a/src/extra_interview_problems/trees/binary_tree.py b/src/extra_interview_problems/trees/binary_tree.py
new file mode 100755
index 0000000..75161d7
--- /dev/null
+++ b/src/extra_interview_problems/trees/binary_tree.py
@@ -0,0 +1,122 @@
+#!/usr/bin/python
+
+__author__ = "bt3"
+
+
+class Node(object):
+
+ def __init__(self, item=None,):
+
+ self.item = item
+ self.left = None
+ self.right = None
+
+ def __repr__(self):
+ return '{}'.format(self.item)
+
+
+ def _add(self, value):
+ new_node = Node(value)
+
+ if not self.item:
+ self.item = new_node
+ elif not self.left:
+ self.left = new_node
+ elif not self.right:
+ self.right = new_node
+ else:
+ self.left = self.left._add(value)
+ return self
+
+
+ def _search(self, value):
+ if self.item == value:
+ return True # or self
+
+ found = False # or False, thats diff from BST
+ if self.left:
+ found = self.left._search(value)
+
+ if self.right:
+ found = found or self.right._search(value)
+
+ return found
+
+
+ def _isLeaf(self):
+ return not self.right and not self.left
+
+
+
+class BT(object):
+
+ def __init__(self):
+ self.root = None
+
+
+ def add(self, value):
+ if not self.root:
+ self.root = Node(value)
+ else:
+ self.root._add(value)
+
+
+ def printPreorder(self):
+ current = self.root
+ nodes, stack = [], []
+ while stack or current:
+ if current:
+ nodes.append(current.item) # this is what change
+ stack.append(current)
+ current = current.left
+ else:
+ current = stack.pop()
+ current = current.right
+ print nodes
+
+
+ def printPostorder(self):
+ current = self.root
+ nodes, stack = [], []
+ while stack or current:
+
+ if current:
+ stack.append(current)
+ current = current.left
+ else:
+ current = stack.pop()
+ nodes.append(current.item) # this is what change
+ current = current.right
+ print nodes
+
+
+ def search(self, value):
+ if self.root:
+ return self.root._search(value)
+
+
+
+
+if __name__ == '__main__':
+
+ bt = BT()
+ print "Adding nodes 1 to 10 in the tree..."
+ for i in range(1, 11):
+ bt.add(i)
+
+ print
+ print "Searching for nodes 16 and 6"
+ print bt.search(16)
+ print bt.search(6)
+
+ print
+ print "Printing preorder..."
+ bt.printPreorder()
+
+ print
+ print "Printing postorder..."
+ bt.printPostorder()
+
+ print
+ print "Printing Inorder..."
+ bt.printInorder()
\ No newline at end of file
diff --git a/src/extra_interview_problems/trees/check_if_balanced.py b/src/extra_interview_problems/trees/check_if_balanced.py
new file mode 100755
index 0000000..568cec0
--- /dev/null
+++ b/src/extra_interview_problems/trees/check_if_balanced.py
@@ -0,0 +1,30 @@
+__author__ = "bt3"
+
+
+from binary_search_tree import BST, Node
+from binary_tree import BT, Node
+
+
+
+def isBalanced(node, left=0, right=0):
+ if not node:
+ return (left - right) < 2
+
+ return isBalanced(node.left, left+1, right) and \
+ isBalanced(node.right, left, right+1)
+
+
+
+
+if __name__ == '__main__':
+ bt = BST()
+ for i in range(1, 10):
+ bt.add(i)
+
+ assert(isBalanced(bt.root) == True)
+
+ bt = BT()
+ for i in range(1, 10):
+ bt.add(i)
+
+ assert(isBalanced(bt.root) == False)
diff --git a/src/extra_interview_problems/trees/check_if_bst.py b/src/extra_interview_problems/trees/check_if_bst.py
new file mode 100755
index 0000000..b089ef0
--- /dev/null
+++ b/src/extra_interview_problems/trees/check_if_bst.py
@@ -0,0 +1,62 @@
+__author__ = "bt3"
+
+
+from binary_search_tree import BST, Node
+from binary_tree import BT, Node
+
+
+def isBST(node, min_node=float("-infinity"), maxVal=float("infinity")):
+ if not node:
+ return True
+
+ if not min_node <= node.item <= maxVal:
+ return False
+
+ return isBST(node.left, min_node, node.item) and \
+ isBST(node.right, node.item, maxVal)
+
+
+
+def isBST_other_method(node, max_node=None, min_node=None):
+
+ if not node:
+ return True
+
+ left, right = True, True
+ min_node = min_node or float('inf')
+ max_node = max_node or -float('inf')
+
+ if node.left:
+ if node.left.item > node.item or node.left.item > max_node:
+ left = False
+ else:
+ max_node = node.item
+ left = isBST(node.left, max_node, min_node)
+
+ if node.right:
+ if node.right.item < node.item or node.right.item < min_node:
+ rihjt = False
+ else:
+ min_node = node.item
+ right = isBST(node.right, max_node, min_node)
+
+ return left and right
+
+
+
+
+
+if __name__ == '__main__':
+ bt = BST()
+ for i in range(1, 10):
+ bt.add(i)
+
+ assert(isBST(bt.root) == True)
+
+ bt = BT()
+ for i in range(1, 10):
+ bt.add(i)
+
+ assert(isBST(bt.root) == False)
+
+
diff --git a/src/extra_interview_problems/glassdoor/2015/transversing_bt.py b/src/extra_interview_problems/trees/transversing_bt.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/transversing_bt.py
rename to src/extra_interview_problems/trees/transversing_bt.py
diff --git a/src/extra_interview_problems/glassdoor/2015/trie.py b/src/extra_interview_problems/trees/trie.py
similarity index 100%
rename from src/extra_interview_problems/glassdoor/2015/trie.py
rename to src/extra_interview_problems/trees/trie.py