POJ

#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<string>
#include<cstring>
#include<set>
#include<map>
#include<list>
#include<queue>
#include<vector>
#define tree int o,int l,int r
#define lson o<<1,l,mid
#define rson o<<1|1,mid+1,r
#define lo o<<1
#define ro o<<1|1
#define ULL unsigned long long
#define LL long long
#define UI unsigned int
#define inf 0x7fffffff
#define eps 1e-7
#define N 1000009
#define M 20009
using namespace std;
int T,n,m,k,t;
char str[N];
int dp[13][1110010];
int main()
{
#ifndef ONLINE_JUDGE
    freopen("ex.in","r",stdin);
#endif
    while (scanf("%d%d",&n,&m)!=EOF)
    {
        memset(dp,0,sizeof(dp));
        scanf("%s",str);
        n=strlen(str);
        str[n+m]='';
        for(int i=0; i<n+m-1; i++)
        {
            int sum=0;
            if(i>=n-1)str[i+1]='0';//要先处理！
            for(int j=0;j<13&&i-j>=0;j++)
            {
                if(str[i-j]-'0')
                sum+=(1<<(j));
                if(i>=n-1&&dp[j][sum])
                {
                    str[i+1]=str[dp[j][sum]];
                }
                dp[j][sum]=i+1;
            }
        }
        cout<<str+n<<endl;
    }
    return 0;
}