#include <bits/stdc++.h>   using namespace std;   using ll = long long;   #define f(i,q,n) for(int i=(int)q;i<n;i++)   #define pb push_back   #define debug(x) cout<<#x<<   <<x<<endl;   int main()   {       ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);       int t=1;       cin>>t;       while(t--){           int n,m;           cin>>n>>m;           string s;           cin>>s;           while(m--){           string ans=s;           f(i,0,n){               if(i==0 and ans[i]== 0  and ans[i+1]== 1 ){s[i]= 1 ;}               else if(i==n-1 and ans[i]== 0  and ans[i-1]== 1 ){s[i]= 1 ;}               else{                   if(i<n-1 and i>0 and ans[i]== 0  and ans[i+1]!=ans[i-1]){                       s[i]= 1 ;                   }               }           }           if(s==ans){               break;           }                 }                  cout<<s<<endl;          }       return 0;   }   //check constraints, testcases, ll vs int    