#include <bits/stdc++.h>
#define rep(i, f, t) for(int i(f); i <= t; ++i)
#define re(i, t) for(int i(1); i <= t; ++i)
#define per(i, t, f) for(int i(t); i >= f; --i)
#define pe(i, t) for(int i(t); i >= 1; --i) 
#define nx(i, u) for(int i(head[u]); i; i = e[i].nxt)
typedef long long ll;
typedef unsigned long long ull; 
using namespace std;
typedef pair <int, int> pii;
#define pb push_back
#define eb emplace_back 
#define fi first
#define se second
#define Ls (ix(l, mid))
#define Rs (ix(mid+1, r))
#define ix(l, r) ((l + r) | (l != r))  
#define mp(i, j) (make_pair(i, j))
//#define int long long
#define inf 0x3f3f3f3f
#define i128 __int128  
#define INF 0x3f3f3f3f3f3f3f3f
namespace IO {
char buf[1 << 21], *p1 = buf, *p2 = buf, buf1[1 << 21];
inline char gc() {return p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 21, stdin), p1 == p2) ? EOF : *p1++;}
template<class I>
inline void read(I &x) {x = 0;I f = 1;char c = gc();while (c < '0' || c > '9') {if (c == '-') {f = -1;} c = gc();}while (c >= '0' && c <= '9') {x = x * 10 + c - '0';c = gc();}x *= f;}
template<class I>
inline void write(I x) {if (x == 0) {putchar('0');return;}I tmp = x > 0 ? x : -x;if (x < 0) {putchar('-');}int cnt = 0;while (tmp > 0) {buf1[cnt++] = tmp % 10 + '0';tmp /= 10;}while (cnt > 0)putchar(buf1[--cnt]);}
#define outn(x) write(x), putchar('\n')
#define out(x) write(x), putchar(' ')
} using namespace IO;
#define look_memory cerr<<abs(&sT-&eD)/1024.0/1024<<'\n'
int sT;

const int N = 4e6 + 5;
int T, n, m;
char s[N];
int a[N], b[N];
 
int pos[N], ax[N], ay[N];

void solve () {
	if(n < m) swap(n, m);
	int len = n + m + 2; 
	int L = 0;
	int sz = 0;
	re(i, m) {
		sz += (!a[i]);
		if(a[i]) {
			pos[++L] = m-i+1;
			ay[m-i+1] = 1;
		}
	}
	rep(i, m+1, n+m) {
		if(a[i]) ax[n-(i-m)+1] = 1;
	}  
	
	rep(i, m+1, n+m) { 
		if(!a[i]) {
			++sz;
			if(sz > m) break; 
			if(pos[L] > (n-(i-m)+1)) break;
			ay[pos[L]] = 0;
			--L;
			ax[n-(i-m)+1] = 1;
		} 
	}
	re(i, len) {
		b[i] = ax[i] + ay[i];
	}
	re(i, len) {
		b[i+1] += b[i]/2;
		b[i] &= 1;
	} 
	len = 1;
	re(i, n+m+2) { 
		if(b[i]) len = i;
	} 
	pe(i, len) {
		if(b[i]) putchar('1');
		else putchar('0');
	}
	puts(""); 
	re(i, n+m+2) {
		ax[i] = ay[i] = b[i] = 0;
	}
}	 
 
int main (){ 
	scanf("%d", &T);
	while(T--) {
		scanf("%d %d %s", &n, &m, s + 1);
		re(i, n+m) a[i] = s[i] - '0';
		solve();
	}
	return 0;
}