#include <bits/stdc++.h>
using namespace std;

int main() 
{
    int t; 
    cin >> t;
    
    while (t--) 
    {
        int n, k;
        cin >> n >> k;
        string samp;
        cin >> samp;
        
        int max_ones = 0, count = 0;
        for (int i = 0; i < samp.length(); i++)
        {
            if (samp[i] == '1')
            {
                count++;
            } else {
                count = 0;
            }
            max_ones = max(max_ones, count);
        }
        
        int str = max_ones;
        
        int sum = 0;
        for (int i = 0; i < samp.length() - 1; i++) 
        {
            if (samp[i] == '1' && samp[i + 1] == '0')
            {
                if(k > 0)
                {
                    sum++;
                    k--;
                    i++;
                }
            }
        }

        if(k == 0 && sum > 0) 
        {
            cout << sum + str << endl;
        }
        else 
        {
            cout << str << endl;
        }
    }
    
    return 0;
}