The 15th Zhejiang University Programming Contest

Find the Spy

#include<iostream>
#include<algorithm>
#define maxn 105
#define maxsize 100000000
using namespace std;
int n,cas,i,j,ans;
int a[maxn];
bool ishas[maxsize];
bool compare(int a,int b)
{
    return a < b;
}
int main(void)
{
    cin >> cas;
    while(cas --)
    {
        cin >> n;
        for(i = 0;i < n;i ++){
            cin >> a[i];
        }
        sort(a,a+n,compare);
        if(a[0] != a[1])
            ans = a[0];
        else if(a[n-1] != a[n-2])
                ans = a[n-1];
        else
        {
            for(i = 1;i < n-1;i ++)
            {
                if(a[i] != a[i-1]&&a[i] != a[i+1])
                    ans = a[i];
            }
        }
        cout << ans << endl;
    }
    return 0;
}