#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( sum > 0)
        {
            cout<<sum+str<<endl;
        }
        else 
        {
            cout<<str<<endl;
        }
    }
}