#include<bits/stdc++.h>
using namespace std;
#define int long long
int n, m;
string s;
bool check(int mid)
{
    int cnt = 0;
    for(int i = 1; i <= n; i ++ )
    {
        if(s[i] == '1')
        {
            cnt ++ ;
            i = i + mid - 1;
        }
    }
    return cnt > m;
}
void solve()
{
    std:: cin >> n >> m;
    std:: cin >> s;
    s = " " + s;

    int l = 0, r = 1e18;
    while(l < r)
    {
        int mid = (l + r + 1) / 2;
        if(check(mid))
        {
            l = mid;
        }
        else
        {
            r = mid - 1;
        }
    }

    std:: cout << l + 1 << endl;
}   
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
    int T;
    std:: cin >> T;
    while(T -- )
	solve();
	return 0;
}