PAT (Advanced) 1041. Be Unique (20)

原题：1041. Be Unique (20)

解题思路：
设个计数器即可。

代码如下：#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
const int maxn = 10000 + 5;

int cnt[maxn];
vector<int> num;
int main()
{
int n;
while(scanf("%d", &n) == 1)
{
memset(cnt, 0, sizeof(cnt));
for(int i = 0; i < n; i++)
{
int x;
scanf("%d", &x);
num.push_back(x);
cnt[x]++;
}
int ans = -1;
for(int i = 0; i < num.size(); i++)
if(cnt[num[i]] == 1) {ans = num[i]; break;}
if(ans == -1) printf("None\n");
else printf("%d\n", ans);
}
return 0;
}