/*
    BISMILLAHIR RAHMANIR RAHIM
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
void solve()
{
    int n,k;cin>>n>>k;
    string s;cin>>s;
    vector<pair<char,int>> conse;
    conse.push_back({s[0],1});
    int cnt=0;
    for(int i=1;i<n;i++)
    {
       if(conse.back().first==s[i])
       {
        conse.back().second++;
       }
       else{
        conse.push_back({s[i],1});
       }
    }
    vector<int> ones;
    for(auto it:conse)
    {
        if(it.first=='1')
        {
            ones.push_back(it.second);
        }
    }
    sort(ones.rbegin(),ones.rend());
    if(k>=ones.size())
    {
        int ans=0;
        for(auto it:ones)
        {
            ans+=it;
        }
        cout<<ans<<endl;
    }
    else{
        int ans=0;
        for(int i=0;i<=k;i++)
        {
            ans+=ones[i];
        }
        cout<<ans<<endl;
    }
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t=1;
    cin>>t;
    while(t--)
    {
      solve();
    }
    return 0;
}