glassdoor 2014

src/extra_interview_problems/glassdoor/2014/math_arrays_and_strings/fibonacci.py

@@ -1,8 +1,7 @@
 #!/usr/bin/env python
 
 
-__author__ = "Mari Wahl"
-__email__ = "marina.w4hl@gmail.com"
+__author__ = "bt3"
 
  ''' understanding generators'''
 

src/extra_interview_problems/glassdoor/2015/alpha_permutation.py

@@ -0,0 +1,34 @@
+#!/bin/python
+
+''' Write code to generate all possible case permutations of a given
+lower-cased string
+'''
+
+def alpha_permutation(string):
+    '''
+    >>> alpha_permutation('0ab')
+    ['0Ab', '0Ab', '0ab', '0ab', '0Ba', '0Ba', '0ba', '0ba', 'ab0', 'a0b', 'a0b', 'b0a', 'b0a', 'ba0']
+    >>> alpha_permutation('')
+    ''
+    '''
+
+    if len(string) < 2:
+        return string
+
+    result = []
+
+    for i, c in enumerate(string):
+        rest =  string[i+1:] + string[:i]
+        for cc in alpha_permutation(rest):
+            if cc.isalpha():
+                result.append(c.upper() + cc)
+            result.append(c + cc)
+
+    return result
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+

src/extra_interview_problems/glassdoor/2015/anagram.py

@@ -0,0 +1,31 @@
+#!/bin/python
+
+from collections import Counter
+
+def is_anagram(s1, s2):
+    '''
+    >>> is_anagram('cat', 'tac')
+    True
+    >>> is_anagram('cat', 'hat')
+    False
+    '''
+    counter = Counter()
+    for c in s1:
+        counter[c] += 1
+
+    for c in s2:
+        counter[c] -= 1
+
+    for i in counter.values():
+        if i:
+            return False
+
+    return True
+
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+

src/extra_interview_problems/glassdoor/2015/anagram_sorting.py

@@ -1,11 +0,0 @@
-#!/bin/python
-
-'''
- anagram sorting. huge list that does not fit in memory?
-'''
-
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
-

src/extra_interview_problems/glassdoor/2015/bucket.py

@@ -1,19 +0,0 @@
-#!/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()
-

src/extra_interview_problems/glassdoor/2015/check_if_palindrome.py

@@ -1,6 +1,5 @@
 #!/bin/python
 
-''' Determine if an Array of integers contains 3 numbers that sum to 0 '''
 
 from collections import defaultdict
 

src/extra_interview_problems/glassdoor/2015/comb.py

@@ -1,11 +0,0 @@
-#!/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()
-

src/extra_interview_problems/glassdoor/2015/find_longest_str_unique_chars.py

@@ -0,0 +1,35 @@
+#!/bin/python
+
+'''
+given a string, find longest string with unique characters
+'''
+
+def find_longest(string):
+    '''
+    >>> find_longest('abfgrhgtrdsandwejfhdasjcbdsjvrejwghireeej')
+    'wejfhdas'
+    >>> find_longest('abcabcabcabcdefabcccc')
+    'defabc'
+    '''
+    maxs = ''
+    result = ''
+
+    for c in string:
+        if c in result:
+            if len(maxs) < len(result):
+                maxs = result
+            result = ''
+        else:
+            result += c
+
+    if result and len(maxs) < len(result):
+        maxs = result
+
+    return maxs
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+

src/extra_interview_problems/glassdoor/2015/find_nth_fibonacci.py

@@ -6,6 +6,28 @@ Optimize your code so that the numbers
 don't have to be recalculated on consecutive function call
 '''
 
+def fib(n):
+    '''
+    >>> fib(2)
+    1
+    >>> fib(5)
+    5
+    >>> fib(7)
+    13
+    '''
+
+    if n < 3:
+        return 1
+
+    a, b = 0, 1
+    count = 1
+
+    while count < n:
+        count += 1
+        a, b = b, a+b
+
+    return b
+
 
 if __name__ == '__main__':
     import doctest

src/extra_interview_problems/glassdoor/2015/find_prime_factors.py

@@ -0,0 +1,34 @@
+#!/bin/python
+
+'''
+find prime factors of a number.
+'''
+
+import math
+
+def find_prime_factors(n):
+    '''
+    >>> find_prime_factors(14)
+    [2, 7]
+    >>> find_prime_factors(19)
+    []
+    '''
+
+    divisors = [d for d in range(2, n//2 + 1) if n % d == 0]
+    primes = [d for d in divisors if is_prime(d)]
+
+    return primes
+
+
+def is_prime(n):
+    for j in range(2, int(math.sqrt(n))):
+        if (n % j) == 0:
+            return False
+    return True
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+

src/extra_interview_problems/glassdoor/2015/long_string.py

@@ -1,12 +0,0 @@
-#!/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()
-

src/extra_interview_problems/glassdoor/2015/longest_common_prefix.py

@@ -0,0 +1,38 @@
+#!/bin/python
+
+'''
+Given two strings, write a function
+to calculate the longest common prefix (LCP) of the strings.
+'''
+
+def lcp(s1, s2):
+    '''
+    >>> lcp('dabbd', 'aabbaa')
+    3
+    >>> lcp('abcd', 'hi')
+    0
+    '''
+
+    p1 = 0
+    aux, lcp = '', ''
+    string1 = min(s1, s2)
+    string2 = max(s1, s2)
+
+    while p1 < len(string1):
+        p2 = 0
+        while  p2 < len(string2) and p1+p2 < len(string1):
+            if string1[p1+p2] == string2[p2]:
+                aux += string1[p1+p2]
+            else:
+                if len(lcp) < len(aux):
+                    lcp = aux
+                aux = ''
+            p2 += 1
+        p1 += 1
+
+    return len(lcp)
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+

src/extra_interview_problems/glassdoor/2015/longest_str.py

@@ -1,11 +0,0 @@
-#!/bin/python
-
-'''
-given a string, find longest string with unique characters
-'''
-
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
-

src/extra_interview_problems/glassdoor/2015/permutations.py

@@ -2,15 +2,22 @@
 
 ''' Generate all permutations of an alphanumeric string '''
 
-    def get_permutations(word):
-        if len(word) < 2:
-            yield word
-            return
+def permutations(word):
+    '''
+    >>> permutations('abc')
+    ['abc', 'acb', 'bac', 'bca', 'cab', 'cba']
+    >>> permutations('')
+    ''
+    '''
+    if len(word) < 2:
+        return word
 
-        for i in range(len(word)):
-            rest = word[:i] + word[i+1:]
-            for tail in get_permutations(rest):
-                yield word[i] + tail
+    res = []
+    for i in range(len(word)):
+        rest = word[:i] + word[i+1:]
+        for p in permutations(rest):
+            res.append(word[i] + p)
+    return res
 
 
 

src/extra_interview_problems/glassdoor/2015/primes.py

@@ -1,11 +0,0 @@
-#!/bin/python
-
-'''
-find prime factors of a number.
-'''
-
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
-

src/extra_interview_problems/glassdoor/2015/rec_bt.py

@@ -1,12 +0,0 @@
-#!/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()
-

src/extra_interview_problems/glassdoor/2015/smallest_bst.py

@@ -1,11 +0,0 @@
-#!/bin/python
-
-'''
-find the smallest number in a BST
-'''
-
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
-

src/extra_interview_problems/glassdoor/2015/transversing_bt.py

@@ -0,0 +1,50 @@
+#!/bin/python
+
+'''
+Reconstruct a binary tree given two sequences of node traversals,
+one from inorder and one from postorder traversal.
+'''
+
+class Node(object):
+    def __init__(self, value, right=None, left=None):
+        self.value = value
+        self.right = right
+        self.left = left
+
+def create_tree():
+    tree = Node(4)
+    tree.right = Node(6)
+    tree.left = Node(2)
+    tree.right.left = Node(5)
+    tree.right.right = Node(7)
+    tree.left.left = Node(1)
+    tree.left.right = Node(3)
+    return tree
+
+def inorder(tree):
+    if tree:
+        if tree.left:
+            inorder(tree.left)
+        print tree.value
+        if tree.right:
+            inorder(tree.right)
+
+def postorder(tree):
+    if tree:
+        if tree.left:
+            postorder(tree.left)
+        if tree.right:
+            postorder(tree.right)
+        print tree.value
+
+
+
+
+
+if __name__ == '__main__':
+    tree = create_tree()
+    print 'Printing inorder...'
+    inorder(tree)
+    print
+    print 'Printing postorder...'
+    postorder(tree)

src/extra_interview_problems/glassdoor/2015/trie.py

@@ -2,11 +2,61 @@
 
 '''
 Implement a trie. (Write the API and code for inserting into a trie).
-
 '''
 
+def make_trie(*args):
+    trie = {}
+
+    for word in args:
+        temp_trie = trie
+        for letter in word:
+            temp_trie = temp_trie.setdefault(letter, {})
+        temp_trie = temp_trie.setdefault('_end_', '_end_')
+
+    return trie
+
+
+def in_trie(trie, word):
+    temp_trie = trie
+    for letter in word:
+        if letter not in temp_trie:
+            return False
+        temp_trie = temp_trie[letter]
+    return True
+
+
+def remove_from_trie(trie, word, depth):
+    if word and word[depth] not in trie:
+        return False
+
+    if len(word) == depth + 1:
+        del trie[word[depth]]
+        if not trie:
+           return True
+        return False
+    else:
+        temp_trie = trie
+
+        if remove_from_trie(temp_trie[word[depth]], word, depth + 1):
+            if temp_trie:
+                del temp_trie[word[depth]]
+            return not temp_trie
+    return False
+
 
 if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
+    trie = make_trie('hello', 'abc', 'baz', 'bar', 'barz')
+    print 'This is the trie:'
+    print trie
+
+    assert(in_trie(trie, 'hello') == True)
+    assert(in_trie(trie, 'bar') == True)
+    assert(in_trie(trie, 'bab') == False)
+    assert(in_trie(trie, 'zzz') == False)
+
+    remove_from_trie(trie, 'abc', 0)
+    assert(in_trie(trie, 'abc') == False)
+
+
+