Single Number
Given an array of integers, every element appears twice except for one. Find that single one.
python code:
class Solution:
    # @param {integer[]} nums
    # @return {integer}
    def singleNumber(self, nums):
          B={}
          for i in nums:
                if i not in B:      #建立一个dict,遍历此list,将其值作为key,并简单的将其出现次数离散化为1和2作为value
                      B[i]=1
                else:
                      B[i]=2
          for i in B:
                if B[i] == 1:
                      ret=i        #遍历dict,如果某个key对应的value为1,则返回该值
                      break
          return ret
原文:http://www.cnblogs.com/bthl/p/4574519.html