#include<bits/stdc++.h>
using namespace std;
#define ll long long int 
int main()
{
  ll tc;
    cin>>tc;
    while(tc--)
    {
        ll n,k;
        cin>>n>>k;
        string s;
        cin>>s;
        ll c=0;
        vector<ll>v;
        for(int i=0;i<n;i++)
        {
            if(s[i]=='1')
                c++;
            else if(s[i]=='0' && c>0)
            {
                v.push_back(c);
                c=0;
            }
            if(s[i]=='0') c=0;
        }
        if(c>0)
            v.push_back(c);
     
       sort(v.rbegin(),v.rend());
        ll ans=0;
        for(int i=0;i<=min((ll)v.size()-1,k);i++)
            ans+=v[i];
        cout<<ans<<endl;
    }
}