leetcode 30day--1
Single Number
Given a non-empty array of integers, every element appears twice except for one. Find that single one.
Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
Example 1:
Input: [2,2,1] Output: 1
Example 2:
Input: [4,1,2,1,2] Output: 4
class Solution { public: //异或 // 1 ^ 1 = 0 int singleNumber(vector<int>& nums) { int res = nums[0]; for(int i=1;i<nums.size();i++){ res ^= nums[i]; } return res; } };
或者利用hash表