PAT 1041. Be Unique

题目：http://pat.zju.edu.cn/contests/pat-a-practise/1041

思路：STL map简单应用

代码：

#include<cstdio>#include<cstring> #include<map>using namespace std;map<int,int> mapp;int main(){int i,n,num[100001];scanf("%d",&n);for(i=0;i<n;i++){   scanf("%d",&num[i]);   mapp[num[i]]++;}for(i=0;i<n;i++)if(mapp[num[i]]==1){  printf("%d\n",num[i]);  return 0;}printf("None\n");return 0;}