#include <bits/stdc++.h>
using namespace std;

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    int T;
    cin >> T;
    while (T--) {
        int n, m;
        cin >> n >> m;
        string S, A, B;
        cin >> S;
        assert (S.size() == n + m);
        const int orgn = n, orgm = m;
        for (char c: S) {
            if (c == '1') {
                if (n > m) {
                    A += c;
                    --n;
                } else {
                    B += c;
                    --m;
                }
            } else {
                if (m == 0 || (n <= m && n > 0)) {
                    A += c;
                    --n;
                } else {
                    B += c;
                    --m;
                }
            }
        }
        n = orgn, m = orgm;
        assert (A.size() == n);
        assert (B.size() == m);
        reverse(A.begin(), A.end());
        reverse(B.begin(), B.end());
        string C(max(n, m), '\0');
        int carry = 0;
        for (int i = 0; i < max(n, m); i++) {
            int x = carry + (i < n ? A[i] - '0' : 0) + (i < m ? B[i] - '0' : 0);
            C[i] = char(x % 2 + '0');
            carry = x / 2;
        }
        if (carry) {
            assert (carry == 1);
            C += char(carry + '0');
        }
        while (C.size() > 1 && C.back() == 0)
            C.pop_back();
        reverse(C.begin(), C.end());
        cout << C << '\n';
    }
    return 0;
}