From ee01cd9446fbfd13bb6b6c60fa8b41e08b71915e Mon Sep 17 00:00:00 2001
From: Mari Wahl <mari.wahl9@gmail.com>
Date: Mon, 5 Jan 2015 22:16:56 -0500
Subject: [PATCH] simple examples, glassdoor

---
 .../advanced/lru_cache.py                     | 15 ++++++
 .../glassdoor/2015/anagram_sorting.py         | 11 ++++
 .../glassdoor/2015/array_3_numbers.py         | 33 ++++++++++++
 .../glassdoor/2015/binary_search.py           | 53 +++++++++++++++++++
 .../glassdoor/2015/bucket.py                  | 19 +++++++
 .../glassdoor/2015/comb.py                    | 11 ++++
 .../glassdoor/2015/fib.py                     | 13 +++++
 .../glassdoor/2015/long_string.py             | 12 +++++
 .../glassdoor/2015/longest_str.py             | 11 ++++
 .../glassdoor/2015/merge.py                   | 44 +++++++++++++++
 .../glassdoor/2015/overlapping.py             | 32 +++++++++++
 .../glassdoor/2015/pairs.py                   | 41 ++++++++++++++
 .../glassdoor/2015/palindrome.py              | 31 +++++++++++
 .../glassdoor/2015/permutations.py            | 20 +++++++
 .../glassdoor/2015/primes.py                  | 11 ++++
 .../glassdoor/2015/rec_bt.py                  | 12 +++++
 .../glassdoor/2015/smallest_bst.py            | 11 ++++
 .../glassdoor/2015/sum_str.py                 | 38 +++++++++++++
 .../glassdoor/2015/tree.py                    | 53 +++++++++++++++++++
 .../glassdoor/2015/trie.py                    | 12 +++++
 .../trees_paths/binary_search_tree.py         |  1 -
 .../trees_paths/binary_tree.py                |  1 -
 .../trees_paths/check_whether_bst.py          |  3 +-
 .../trees_paths/lowest_common_ancestor.py     |  1 -
 .../trees_paths/transversal_BST_ancestor.py   |  1 -
 25 files changed, 484 insertions(+), 6 deletions(-)
 create mode 100644 src/extra_interview_problems/advanced/lru_cache.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/anagram_sorting.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/array_3_numbers.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/binary_search.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/bucket.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/comb.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/fib.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/long_string.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/longest_str.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/merge.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/overlapping.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/pairs.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/palindrome.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/permutations.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/primes.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/rec_bt.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/smallest_bst.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/sum_str.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/tree.py
 create mode 100644 src/extra_interview_problems/glassdoor/2015/trie.py

diff --git a/src/extra_interview_problems/advanced/lru_cache.py b/src/extra_interview_problems/advanced/lru_cache.py
new file mode 100644
index 0000000..5938ac0
--- /dev/null
+++ b/src/extra_interview_problems/advanced/lru_cache.py
@@ -0,0 +1,15 @@
+#!/bin/python3
+
+from functools import lru_cache
+
+
+@lru_cache(maxsize=20)
+def fib(n):
+    if n < 2:
+        return n
+    return fib(n-1) + fib(n-2)
+
+
+if __name__ == '__main__':
+    print([fib(n) for n in range(10)])
+    print(fib.cache_info())
diff --git a/src/extra_interview_problems/glassdoor/2015/anagram_sorting.py b/src/extra_interview_problems/glassdoor/2015/anagram_sorting.py
new file mode 100644
index 0000000..3beefd7
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/anagram_sorting.py
@@ -0,0 +1,11 @@
+#!/bin/python
+
+'''
+ anagram sorting. huge list that does not fit in memory?
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/array_3_numbers.py b/src/extra_interview_problems/glassdoor/2015/array_3_numbers.py
new file mode 100644
index 0000000..fa6face
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/array_3_numbers.py
@@ -0,0 +1,33 @@
+#!/bin/python
+
+''' Determine if an Array of integers contains 3 numbers that sum to 0 '''
+
+from collections import defaultdict
+
+def find_3_number(array):
+    '''
+    >>> find_3_number([1,5,56,11,-3,-12])
+    1 11 -12
+    True
+    >>> find_3_number([] )
+    False
+    '''
+    hash_ = defaultdict()
+    for i in array:
+        hash_[i] = 1
+
+    for i, x in enumerate(array):
+        for y in array[i+1:]:
+            if -(x+y) in hash_:
+                print x, y, -(x+y)
+                return True
+
+    return False
+
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/binary_search.py b/src/extra_interview_problems/glassdoor/2015/binary_search.py
new file mode 100644
index 0000000..10d29a4
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/binary_search.py
@@ -0,0 +1,53 @@
+#!/bin/python
+
+
+def binary_search_rec(array, item, lo=0, hi = None):
+    '''
+    >>> binary_search_rec([2,3,5,6,8,10,15,23], 15)
+    (True, 6)
+    >>> binary_search_rec([2,3,5,6,8,10,15,23], 4)
+    False
+    '''
+    hi = hi or len(array)
+    if hi < lo :
+        return False
+
+    mid = (hi + lo)//2
+
+    if array[mid] == item:
+        return True, mid
+    elif array[mid] < item:
+        return binary_search_rec(array, item, mid + 1, hi)
+    else:
+        return binary_search_rec(array[:mid], item, lo, mid -1)
+
+
+
+def binary_search_iter(array, item):
+    '''
+    >>> binary_search_iter([2,3,5,6,8,10,15,23], 15)
+    (True, 6)
+    >>> binary_search_iter([2,3,5,6,8,10,15,23], 4)
+    False
+    '''
+    hi = len(array)
+    lo = 0
+
+    while lo < hi:
+        mid = (hi+lo)//2
+        if array[mid] == item:
+            return True, mid
+        elif array[mid] > item:
+            hi = mid
+        else:
+            lo  = mid + 1
+    return False
+
+
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/bucket.py b/src/extra_interview_problems/glassdoor/2015/bucket.py
new file mode 100644
index 0000000..aab792e
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/bucket.py
@@ -0,0 +1,19 @@
+#!/bin/python
+
+'''
+Given a telephone directory which is broken in number of
+files, how would you find a telephone number in it (bucket sort)
+
+-  Quick Sort is a good choice when you have to sort a lot of elements.
+    When you are working with smaller collections, Bucket Sort may be a
+    better choice.
+'''
+
+
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/comb.py b/src/extra_interview_problems/glassdoor/2015/comb.py
new file mode 100644
index 0000000..a43cd5b
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/comb.py
@@ -0,0 +1,11 @@
+#!/bin/python
+
+''' Write code to generate all possible case combinations of a given
+lower-cased string. (e.g. "0ab" -> ["0ab", "0aB", "0Ab", "0AB"])
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/fib.py b/src/extra_interview_problems/glassdoor/2015/fib.py
new file mode 100644
index 0000000..540e27d
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/fib.py
@@ -0,0 +1,13 @@
+#!/bin/python
+
+'''
+Write a function to find the nth Fibonacci number.
+Optimize your code so that the numbers
+don't have to be recalculated on consecutive function call
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/long_string.py b/src/extra_interview_problems/glassdoor/2015/long_string.py
new file mode 100644
index 0000000..717d802
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/long_string.py
@@ -0,0 +1,12 @@
+#!/bin/python
+
+'''
+Given a list of strings, write a function
+to calculate the longest common prefix (LCP) of all those strings.
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/longest_str.py b/src/extra_interview_problems/glassdoor/2015/longest_str.py
new file mode 100644
index 0000000..d4e7f06
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/longest_str.py
@@ -0,0 +1,11 @@
+#!/bin/python
+
+'''
+given a string, find longest string with unique characters
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/merge.py b/src/extra_interview_problems/glassdoor/2015/merge.py
new file mode 100644
index 0000000..1c54ea2
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/merge.py
@@ -0,0 +1,44 @@
+#!/bin/python
+
+'''
+You have two arrays with N integers in them. Merge those arrays using a
+recursive algorithm so that the integers in the final array are sorted.
+'''
+
+def merge_arrays(a1, a2):
+    '''
+    >>> merge_arrays([5, 4, 3], [6, 2, 9])
+    [2, 3, 4, 5, 6, 9]
+    >>> merge_arrays([2, 6], [6, 2])
+    [2, 2, 6, 6]
+    >>> merge_arrays([], [])
+    []
+    '''
+
+    a1.sort()
+    a2.sort()
+
+    merge = []
+    p1, p2 = 0, 0
+
+    while p1 < len(a1) and p2 < len(a2):
+        if a1[p1] <= a2[p2]:
+            merge.append(a1[p1])
+            p1 += 1
+        else:
+            merge.append(a2[p2])
+            p2 +=1
+
+    if a1[p1:]:
+        merge.extend(a1[p1:])
+
+    if a2[p2:]:
+        merge.extend(a2[p2:])
+
+    return merge
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/overlapping.py b/src/extra_interview_problems/glassdoor/2015/overlapping.py
new file mode 100644
index 0000000..9fe6bba
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/overlapping.py
@@ -0,0 +1,32 @@
+#!/bin/python
+
+'''
+given an array of intervals, return max number of non-overlapping intervals
+'''
+
+from collections import defaultdict
+
+def non_overlapping(array):
+    '''
+    >>> non_overlapping([(1,2), (2,5), (1, 6)])
+    [[(1, 2), (2, 5)]]
+    >>> non_overlapping([(1,4), (2,5), (3, 6)])
+    []
+    '''
+    total = []
+
+    for i, t in enumerate(array):
+        start = t[0]
+        end = t[1]
+        for tt in array[i+1:] :
+            if end <= tt[0]:
+                total.append([(start, end), (tt[0], tt[1])])
+
+    return total
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/pairs.py b/src/extra_interview_problems/glassdoor/2015/pairs.py
new file mode 100644
index 0000000..80bbf93
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/pairs.py
@@ -0,0 +1,41 @@
+#!/bin/python
+
+'''
+Given an unsorted array of numbers (that may contain repeated numbers),
+ * data structure that contains all the pairs w/sum equal to  k.
+ * Do not include pairs that are the same numbers in a different order.
+'''
+
+from collections import Counter
+
+def sum_pairs(array, k):
+    '''
+    >>> sum_pairs([1, 4, 2, 7, 1, 3, 10, 15, 3, 1], 6)
+    set([(3, 3)])
+    >>> sum_pairs([1, 4, 2, 7, 1, 3, 10, 15, 3, 1], 0)
+    set([])
+    '''
+
+    results = set()
+    dict = Counter()
+
+    for i in array:
+        dict[i] += 1
+
+    for i in array:
+        if dict[k-i] > 0:
+            if i == k-i and dict[k-i] > 1:
+                    results.add((i, k-i))
+                    dict[k-i] -= 2
+            elif i == k-i:
+                results.add((i, k-i))
+                dict[k-i] -= 1
+
+
+    return results
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/palindrome.py b/src/extra_interview_problems/glassdoor/2015/palindrome.py
new file mode 100644
index 0000000..ab3f5dc
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/palindrome.py
@@ -0,0 +1,31 @@
+#!/bin/python
+
+''' Determine if an Array of integers contains 3 numbers that sum to 0 '''
+
+from collections import defaultdict
+
+def is_palindrome(array):
+    '''
+    >>> is_palindrome('subi no onibus')
+    True
+    >>> is_palindrome('helllo there')
+    False
+    >>> is_palindrome('h')
+    True
+    >>> is_palindrome('')
+    True
+    '''
+    array = array.strip(' ')
+    if len(array) < 2:
+        return True
+
+    if array[0] == array[-1]:
+        return is_palindrome(array[1:-1])
+    else:
+        return False
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/permutations.py b/src/extra_interview_problems/glassdoor/2015/permutations.py
new file mode 100644
index 0000000..0714630
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/permutations.py
@@ -0,0 +1,20 @@
+#!/bin/python
+
+''' Generate all permutations of an alphanumeric string '''
+
+    def get_permutations(word):
+        if len(word) < 2:
+            yield word
+            return
+
+        for i in range(len(word)):
+            rest = word[:i] + word[i+1:]
+            for tail in get_permutations(rest):
+                yield word[i] + tail
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/primes.py b/src/extra_interview_problems/glassdoor/2015/primes.py
new file mode 100644
index 0000000..5ebafc1
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/primes.py
@@ -0,0 +1,11 @@
+#!/bin/python
+
+'''
+find prime factors of a number.
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/rec_bt.py b/src/extra_interview_problems/glassdoor/2015/rec_bt.py
new file mode 100644
index 0000000..798c137
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/rec_bt.py
@@ -0,0 +1,12 @@
+#!/bin/python
+
+'''
+Reconstruct a binary tree given two sequences of node traversals,
+one from inorder and one from postorder traversal.
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/smallest_bst.py b/src/extra_interview_problems/glassdoor/2015/smallest_bst.py
new file mode 100644
index 0000000..9d1cf71
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/smallest_bst.py
@@ -0,0 +1,11 @@
+#!/bin/python
+
+'''
+find the smallest number in a BST
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/sum_str.py b/src/extra_interview_problems/glassdoor/2015/sum_str.py
new file mode 100644
index 0000000..370af13
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/sum_str.py
@@ -0,0 +1,38 @@
+#!/bin/python
+
+'''
+find the sum of two integers represented as strings,
+return the sum as string, i.e "123" and "456" would return "579"
+'''
+
+
+def get_number(s):
+    count = 1
+    num = 0
+    p = len(s) -1
+    while p >= 0:
+        num = num + int(s[p])*count
+        count *= 10
+        p -= 1
+    return num
+
+
+def sum_string(s1, s2):
+    '''
+    >>> sum_string('10', '5')
+    '15'
+    >>> sum_string('0', '1')
+    '1'
+    >>> sum_string('123', '456')
+    '579'
+    '''
+
+    n1 = get_number(s1)
+    n2 = get_number(s2)
+    return str(n2 + n1)
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/glassdoor/2015/tree.py b/src/extra_interview_problems/glassdoor/2015/tree.py
new file mode 100644
index 0000000..a6af0a6
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/tree.py
@@ -0,0 +1,53 @@
+#!/bin/python
+
+'''
+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/trie.py b/src/extra_interview_problems/glassdoor/2015/trie.py
new file mode 100644
index 0000000..c8a93c3
--- /dev/null
+++ b/src/extra_interview_problems/glassdoor/2015/trie.py
@@ -0,0 +1,12 @@
+#!/bin/python
+
+'''
+Implement a trie. (Write the API and code for inserting into a trie).
+
+'''
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
diff --git a/src/extra_interview_problems/trees_paths/binary_search_tree.py b/src/extra_interview_problems/trees_paths/binary_search_tree.py
index 0260fa6..f3da045 100755
--- a/src/extra_interview_problems/trees_paths/binary_search_tree.py
+++ b/src/extra_interview_problems/trees_paths/binary_search_tree.py
@@ -1,7 +1,6 @@
 #!/usr/bin/python
 
 __author__ = "bt3"
-__email__ = "bt33gl@gmail.com"
 
 
 from binary_tree import NodeBT, BinaryTree
diff --git a/src/extra_interview_problems/trees_paths/binary_tree.py b/src/extra_interview_problems/trees_paths/binary_tree.py
index b7d0177..282a28a 100755
--- a/src/extra_interview_problems/trees_paths/binary_tree.py
+++ b/src/extra_interview_problems/trees_paths/binary_tree.py
@@ -1,7 +1,6 @@
 #!/usr/bin/python
 
 __author__ = "bt3"
-__email__ = "bt33gl@gmail.com"
 
 
 
diff --git a/src/extra_interview_problems/trees_paths/check_whether_bst.py b/src/extra_interview_problems/trees_paths/check_whether_bst.py
index c5279d6..7bc3eac 100755
--- a/src/extra_interview_problems/trees_paths/check_whether_bst.py
+++ b/src/extra_interview_problems/trees_paths/check_whether_bst.py
@@ -1,5 +1,4 @@
 __author__ = "bt3"
-__email__ = "bt33gl@gmail.com"
 
 
 """ need to keep track of min and max!!!"""
@@ -38,7 +37,7 @@ def isBST(bt, mintree=None, maxtree=None):
     else:
         right = True
 
-    return  left or right
+    return  left and right
 
 
 
diff --git a/src/extra_interview_problems/trees_paths/lowest_common_ancestor.py b/src/extra_interview_problems/trees_paths/lowest_common_ancestor.py
index 7ecd178..bf5f0f2 100755
--- a/src/extra_interview_problems/trees_paths/lowest_common_ancestor.py
+++ b/src/extra_interview_problems/trees_paths/lowest_common_ancestor.py
@@ -1,7 +1,6 @@
 #!/usr/bin/python
 
 __author__ = "bt3"
-__email__ = "bt33gl@gmail.com"
 
 
 from binary_tree import BinaryTree
diff --git a/src/extra_interview_problems/trees_paths/transversal_BST_ancestor.py b/src/extra_interview_problems/trees_paths/transversal_BST_ancestor.py
index b137a48..75de17f 100755
--- a/src/extra_interview_problems/trees_paths/transversal_BST_ancestor.py
+++ b/src/extra_interview_problems/trees_paths/transversal_BST_ancestor.py
@@ -1,7 +1,6 @@
 #!/usr/bin/python
 
 __author__ = "bt3"
-__email__ = "bt33gl@gmail.com"
 
 
 ''' find the lowest ancestor in a BST '''