求调

#include<bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5;
int n, a[N], T;
int main() {
	scanf("%d", &T);
	while (T--) {
		map<int, int>mp;
		int l = 1, r = 1, ans = -INT_MAX;
		scanf("%d", &n);
		for (int i = 1; i <= n; i++) {
			scanf("%d", &a[i]);
		}
		mp[a[l]]++;
		while (l <= r && r <= n) {
			r++;
			mp[a[r]]++;
			if (mp[a[r]] == 2) {
				ans = max(ans, r - l);
				while (mp[a[r]] != 1) {
					mp[a[l]]--;
					l++;
				}
			}
		}
		printf("%d\n", ans);
	}
	return 0;
}