1AC1RE,大佬求助，c++

 #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
string a,b;
ll n,t,k;
bool check(ll mid){
	ll cnt=0;
	for(int i=1;i<=n;i++){
		b[i]=a[i];
	}
	for(int i=1;i<=n;){
		if(b[i]=='0'){
			i++;
			continue;
		}
		for(int j=1;j<=mid&&i<=n;j++){
			b[i++]='0';
		}
		cnt++;
	}
	return cnt<=k;
}
int main(){
	cin>>t;
	while(t--){
		cin>>n>>k;
		for(int i=1;i<=n;i++){
			cin>>a[i];
		}
		ll l=1,r=n,ans=-1,mid;
		while(l<=r){
			mid=(l+r)>>1;
			if(check(mid)){
				r=mid-1;
				ans=mid;
			}else{
				l=mid+1;
			}
		}
		cout<<ans<<endl;
	}

	return 0;
}