#include<bits/stdc++.h>
using namespace std;
namespace yzm{
    typedef long long ll;typedef unsigned long long ull;
    typedef __int128 i28;typedef unsigned int ui;
    mt19937 rd(time(0));
    template <typename T>
    void read(T &x){
        x=0;char c=getchar();T f=1;
        while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
        while(c>='0'&&c<='9'){x=(x<<3)+(x<<1)+(c^48);c=getchar();}
        x=x*f;return;
    }
    template <typename T>
    void write(T x){
        if(x<0){putchar('-');x=-x;}
        if(x>9)write(x/10);
        putchar(x%10+48);
    }
}using namespace yzm;
const int N = 5e6+10;
const int inf = 0x3f3f3f3f;
char s[N];
int ans[N],num[N],sum[N],pre[N],sum1[N];
int n,m,len0,len1,t,tt,tq;
int main(){
    // freopen("input.txt","r",stdin);
    // freopen("1.out","w",stdout);
    read(t);
    while(t--){
        read(n);read(m);
        for(int i=0;i<=n+m+1;i++){ans[i]=num[i]=pre[i]=sum[i]=sum1[i]=0;}
        len0=n;len1=m;tt=0;tq=0;
        if(len1>len0){swap(len0,len1);}
        scanf("%s",s);
        for(int i=1;i<=n+m;i++){
            sum[i]=sum[i-1]+s[i-1]-'0';
            sum1[i]=sum1[i-1]+((s[i-1]-'0')^1);
            pre[sum1[i]]=max(pre[sum1[i]],i);
        }
        for(int i=1;i<=n+m;i++){
            if(!pre[i])pre[i]=n+m;
        }
        for(int i=0;i<=n+m-1;i++){
            if(s[i]=='1'){
                if(len1&&sum[pre[len1-1+tt]]>=len0-len1+2+tq){ans[len1]++;len1--;}
                else {ans[len0]++;len0--;if(len0<len1){swap(len0,len1);}}
                tq++;
            }else{
                tt++;
                if(len1){len1--;}
                else len0--;
            }
        }
        int x=0;
        for(int i=1;i<=n+m+1;i++){
            ans[i]+=x;x=ans[i]/2;ans[i]%=2;
        }
        bool flag=0;
        for(int i=n+m+1;i>=1;i--){
            if(flag||ans[i]==1){flag=1;write(ans[i]);}
        }
        if(!flag){putchar('0');}
        puts("");
    }
    return 0;
}
/*
100010011
*/
/*
11111010
*/
/*
8 10
001110011111011111
10000110111
*/
/*
3 1
1011
*/