/******************************************
*    AUTHOR:         BHUVNESH JAIN        *
*    INSTITUITION:   BITS PILANI, PILANI  *
******************************************/
#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef long double LD;
typedef pair<int,int> pii;
typedef pair<LL, LL> pll;

#define fi				first
#define sec 			second

const int MAX = 1e5 + 5;

int n, d;
int a[MAX];

int dnc(int i, int j) {
	if (i == j) {
		if (a[i] >= d) {
			return 1;
		}
		return INT_MAX;
	}
	int ans = INT_MAX;
	int m = (i + j) / 2;
	int u = dnc(i, m);
	ans = min(ans, u);
	int v = dnc(m+1, j);
	ans = min(ans, v);
	map<int,int> mp, mp2;
	int sum = 0;
	for(int x = m+1; x <= j; ++x) {
		sum += a[x];
		if (sum >= d) {
			ans = min(ans, x - m);
		}
		if (mp.find(sum) == mp.end()) {
			mp[sum] = x;
			mp2[-sum] = x;
		}
	}
	int last = INT_MAX;
	for(auto it : mp2) {
		mp[-it.fi] = min(mp[-it.fi], last);
		last = min(last, it.sec);
	}
	sum = 0;
	for(int x = m; x >= i; --x) {
		sum += a[x];
		if (sum >= d) {
			ans = min(ans, m - x + 1);
		}
		int req = d - sum;
		auto it = mp.lower_bound(req);
		if (it != mp.end()) {
			ans = min(ans, it->sec - x + 1);
		}
	}
	mp.clear();
	mp2.clear();
	return ans;
}

int main() {
	int t;
	scanf("%d", &t);
	while(t--) {
		scanf("%d %d", &n, &d);
		for(int i = 1; i <= n; ++i) {
			scanf("%d", &a[i]);
		}
		int res = dnc(1, n);
		if (res == INT_MAX) {
			res = -1;
		}
		printf("%d\n", res);
	}
	return 0;
}