complementary_pairs.py

#!/usr/bin/env python

A = [1, 8, -3, 0, 1, 3, -2, 4, 5]

def complementary_pairs(K, A):
    buckets = {}
    for x in A:
        if x not in buckets:
            buckets[x] = 0
        buckets[x] += 1
    N = 0
    for i in buckets:
        N += buckets[i] * buckets.get(K-i, 0)
    return N

print complementary_pairs(6, A)

isAnagramOfPalindrome.py

#!/usr/bin/env python

def isAnagramOfPalindrome(s):
    buckets = {}
    for c in s:
        if c not in buckets:
            buckets[c] = 0
        buckets[c] += 1
    how_many_odds = 0
    for v in buckets.values():
        if v%2:
            how_many_odds += 1
    return how_many_odds<2

if __name__ == '__main__':
    import sys
    s = sys.argv[1]
    print isAnagramOfPalindrome(s)