Leetcode 136. Single Number

136. Single Number

 

Given an 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?

一开始提交的时候居然compile error，一直显示control reaches end of non-void function [-Werror=return-type]。后来加了句return 0；之

后才通过的。如果返回值是除void外的类型，那就必须得保证一定会有一个相应类型的返回值。恍然大悟~

#include<cstdio>#include<iostream>#include<vector>#include<algorithm>using namespace std;/**********************************提交部分**********************************/ class Solution{public:int singleNumber(vector<int>& nums){sort(nums.begin(),nums.end());for(int i=0; i<nums.size(); i=i+2){if(nums[i]!=nums[i+1])return nums[i];}return 0;}};/*****************************************************************************/int main(){Solution S;vector<int> a;int n;scanf("%d",&n);int tmp;for(int i=0; i<n; i++){scanf("%d",&tmp);a.push_back(tmp);}int ans=S.singleNumber(a);printf("%d\n",ans);return 0;}