左端点为L 右端点为R
#include<cstdio>
#include<set>
#include<algorithm>
using namespace std;
const int maxn = 1000000 + 5;
int A[maxn];
int main() {
int T, n;
scanf("%d", &T);
while(T--) {
scanf("%d", &n);
for(int i = 0; i < n; i++) scanf("%d", &A[i]);
set<int> s;
int L = 0, R = 0, ans = 0;
while(R < n) {
while(R < n && !s.count(A[R])) s.insert(A[R++]); //count( )–返回某个值元素的个数
ans = max(ans, R - L);
s.erase(A[L++]);
}
printf("%d\n", ans);
}
return 0;
}