leetcode - single number

singlenum.py

'''
Given an array of integers, every element appears twice except for one. Find that single one.
'''

class Solution:
    # @param A, a list of integer
    # @return an integer
    def singleNumber(self, A):
        A.sort()

        x=0
        y=1
        
        
        if len(A) == 1:
            return A[0]
        else:
            for i in xrange(len(A) / 2):
	            #print x,y,i
	
	            if A[x] != A[y]:
		            return A[x]
		            break
	
	            x = x+2
	            y = y+2
            else:
	            return A[-1]