#include <iostream>
using namespace std;
int main(int argc, const char * argv[]) {
int t,n,k;
string tab;
cin>>t;
for(int f=0;f<t;f++){
cin>>n;
cin>>k;
cin>>tab; //0101000001
int aktualnaIloscJedynek=0;
int max_dl=1, poczatek, dl=1, p=0, pierwszJedynka=0;
poczatek=p=0;
for(int i=0;i<n;i++){
if(tab[i]=='0'){ //sprawdza czy jest rowna 0 jak tak to bez lipy przechodzi dalej
dl++;
//cout<<"i: "<<i<<" "<<0<<"dlugosc- "<<dl<<endl;
if(dl>max_dl){
max_dl=dl;
}
}else{
if(tab[i]=='1' && aktualnaIloscJedynek<k){ //sprawdza czy jest 1 a jak tak czy ilosc jedynek nie jest wieksza niz k
if(aktualnaIloscJedynek==0){
pierwszJedynka=i;
}
dl++;
aktualnaIloscJedynek++;
if(dl>max_dl){
max_dl=dl;
}
}else{
i=pierwszJedynka+1;
aktualnaIloscJedynek=0;
dl=1;
}
}
}
cout<<max_dl<<endl;
}
return 0;
}
/*
10 1
0101000001
*/
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