UVA_11572_Unique_Snowflakes

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <set>
#include <sstream>
#include <stdlib.h>
#include <cmath>
#define LL unsigned long long
using namespace std;
int id[1000001];

int main() {
  int t, n;
  scanf("%d", &t);
  while (t--) {
    map<int, int> mp;
    scanf("%d", &n);
    int ans = 0, begin = 1;
    for (int i = 1; i <= n; i++) {
      scanf("%d", &id[i]);
      if (mp[id[i]] >= begin) {
        begin = mp[id[i]] + 1;
      }
      mp[id[i]] = i;
      ans = max(i-begin+1,ans);
    }
    printf("%d\n", ans);
  }
  return 0;
}