UVa 11572 - Unique Snowflakes

// UVa 11572 - Unique Snowflakes

#include <stdio.h>
#include <map>
using namespace std;

map<int, int> last;

int main() {
	int t;
	for (scanf("%d", &t); t; t--) {
		int n;
		scanf("%d", &n);
		int start = 1, sol = 0;
		last.clear();
		for (int i = 1; i <= n; i++) {
			int a;
			scanf("%d", &a);

			if (last[a] >= start) {
				if (i - start > sol)
					sol = i - start;
				start = last[a] + 1;
			}
			last[a] = i;

		}
		if (n + 1 - start > sol)
			sol = n + 1 - start;
		printf("%d\n", sol);
	}
	return 0;
}