#include<bits/stdc++.h>
#define maxn 1000010

using namespace std;

int t;

int n;

int a[maxn];

int flag[maxn];

int l,r;

int ans;

int main(){
	cin>>t;
	while(t--){
		memset(a,0,sizeof(a));
		memset(flag,0,sizeof(flag));
		l=1,r=1;
		ans=-1;
		cin>>n;
		for(int i=1;i<=n;i++) cin>>a[i];
		for(int l=1;l<=n;l++){
			flag[l-1]--;
			while(l<=r&&r<=n){
				r++;
				flag[a[r]]+=1;
				if(flag[a[r]]==2){
					ans=max(ans,r-l);
					break;
				}
			}
		}
		cout<<ans<<"\n";
	}
	return 0;
}

编译信息显示：UnexpectedResponseStatus: expect status code: 301 Moved Permanently on https://onlinejudge.org/index.php?option=com_comprofiler&task=login , got:`200 OK`