#ifdef Prateek
  #include "Prateek.h"
#else
  #include <bits/stdc++.h>
  using namespace std;
  #define debug(...) 42
#endif
#define F first
#define S second
#define pb push_back
#define int ll
#define f(i,x,n) for(int i=x;i<n;i++)
#define all(c) c.begin(),c.end()
using ll = long long;
const int MOD = 1e9+7, N = 1e5 + 10;
const int M = 20;

int can[1 << M];

void test(){
   int n, k;
   cin >> n >> k;
   string s;
   cin >> s;
   s = "#" + s;
   vector<int> nxt(n + 1);
   nxt[n] = (s[n] == '0') ? n : 1e9;
   for (int i = n - 1; i; --i) {
      if (s[i] == '0') {
         nxt[i] = i;
      } else {
         nxt[i] = nxt[i + 1];
      }
   }
   int m = min(k, 20LL);
   int d = k - m;
   for (int i = 1; i + k - 1 <= n; ++i) {
      if (nxt[i] - i < d) continue;
      int cur = 0;
      for (int j = i + d; j < i + k; ++j) {
         cur = cur * 2 + s[j] - '0';
      }
      can[((1 << m) - 1) ^ cur] = 1;
   }
   int r = -1;
   for (int i = 0; i < (1 << m); ++i) {
      if (can[i] == 0) {
         r = i;
         break;
      }
   }
   for (int i = 1; i + k - 1 <= n; ++i) {
      if (nxt[i] - i < d) continue;
      int cur = 0;
      for (int j = i + d; j < i + k; ++j) {
         cur = cur * 2 + s[j] - '0';
      }
      can[((1 << m) - 1) ^ cur] = 0;
   }
   if (r == -1) {
      cout << "NO\n";
      return;
   }
   cout << "YES\n" << string(d, '0');
   for (int j = m - 1; j >= 0; --j) {
      cout << ((r >> j) & 1);
   }
   cout << '\n';
   return;
}

int32_t main(){
   ios::sync_with_stdio(false);
   cin.tie(NULL);
   int tt = 1;
   cin >> tt;
   f(i,0,tt) test();   
   return 0;
}