#include <bits/stdc++.h>

using namespace std;

#define fast_io ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define F first
#define S second
#define pb push_back
#define all(x) x.begin(), x.end()
#define endl '\n'
#define int long long

const int MOD = 1e9 + 13;
const int MOD1 = 1e9 + 9;
const int K = 31;
string s;
#define int long long

long long arr[1000500], has[1000500];

void createHash() {
    has[0] = s[0] - '0';
    arr[0] = 1;
    for (int i = 1; i < (int)s.size(); i++) {
        arr[i] = (1LL * arr[i - 1] * K * 1LL) % MOD;
        has[i] = (1LL * has[i - 1] * K  + (s[i] - '0') * 1LL) % MOD;
    }
}

int getHash(int l, int r) {
    int fir = (has[r] - 1LL * (1LL * (l == 0 ? 0 : has[l - 1]) * arr[r - l + 1]) % MOD + MOD) % MOD;
    return fir;
}

long long curH = 0, k, n;

void revH(int pos, int tp) {
    if (tp == 0) {
        curH -= (2 * arr[k - pos]);
        curH += MOD;
        curH %= MOD;
        curH += (1 * arr[k - pos]);
        curH %= MOD;

    } else {
        curH -= (1 * arr[k - pos]);
        curH += MOD;
        curH %= MOD;
        curH += (2 * arr[k - pos]);
        curH %= MOD;
    }
}
long long dp[1000100];
void solve() {
    curH = 0;
    cin >> n >> k;
    cin >> s;
    for (int i = 0; i < s.size(); i++) {
        if (s[i] == '0') {
            s[i] = '2';
        } else {
            s[i] = '1';
        }
    }
    set<long long> st;
    createHash();
    for (int i = k - 1; i < s.size(); i++) {
        st.insert(getHash(i - k + 1, i));
    }
    s = "";
    for (int i = 1; i <= k; i++) {
        s += "1";
    }
    createHash();
    curH = has[k - 1];

    int cnt = 0;
    for (int i = 0; i <= k; i++) {
        dp[i] = 0;
    }
    while (dp[0] == 0 && cnt <= 2e6) {
        cnt++;
        if (st.find(curH) == st.end()) {
            cout << "YES\n";
            for (int i = 1; i <= k; i++) {
                cout << dp[i];
            }
            cout << endl;
            return;
        }
        int p = k;
        while (dp[p] == 1) {
            revH(p, 0);
            dp[p] = 0;
            p--;
        }
        dp[p] = 1;
        revH(p, 1);
    }
    cout << "NO\n";
}

signed main() {
    fast_io;
    int q;
    q = 1;
    cin >> q;
    while (q != 0) {
        solve();
        --q;
    }
}