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

#define ll long long
#define nl "\n"
#define ws " "
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(NULL);
#define MOD 1000000007

typedef vector<ll> vi;
typedef vector<pair<ll, ll>> vii;

int main () {
    FASTIO
    int t;
    cin>>t;
    while (t--) {
        int n, k;
        cin>>n>>k;
        string s;
        cin>>s;
        ll cnt = 0;
        vi v;
        for (int i = 0; i < n; i++) {
            if (s[i] == '0') {
                if (cnt > 0) {
                    v.push_back(cnt);
                    cnt = 0;
                }
            } else {
                cnt++;
            }
        }
        if (cnt > 0) {
            v.push_back(cnt);
        }
        sort (v.rbegin(), v.rend());
        ll ans = v[0];
        for (int i = 1; i < (int) v.size(); i++) {
            if (k == 0) {
                break;
            }
            ans += v[i];
            k--;
        }
        cout<<ans<<nl;
    }
    return 0;
}