SCU 4438 Censor

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

const int INF = 0x7FFFFFFF;
const int mod = 1e9 + 7;
const int N = 5e6 + 10;
const int M = 1e4 + 1;
const double eps = 1e-10;
int T,n,m;

char w[N],p[N];
int L[N],R[N],h;
int lenp,lenw;
int t[N];
int nt[N];

void init()
{
    nt[0] = -1;
    for (int i = 0; w[i]; i++)
    {
        int k = nt[i];
        while (k >= 0 && w[i] != w[k]) k = nt[k];
        nt[i + 1] = k + 1;
    }
}

int main()
{
    while(~scanf("%s%s",w,p+1))
    {
        lenp=strlen(p+1); lenw = strlen(w);
        for(int i=1;i<=lenp;i++) L[i]=i-1,R[i]=i+1;

        init(); R[0]=1; L[lenp+1] = lenp; t[0]=nt[1];

        for (int i = R[0], j = nt[1]; p[i];)
        {
            t[i]=j;

            if (j < 0 || p[i] == w[j])
            {
                i=R[i], j++;
                if (!w[j])
                {
                    int sum=0;
                    for(int u=L[i];;u=L[u])
                    {
                        if(sum==lenw)
                        {
                            j=t[u];
                            i=u;
                            if(i==0) i=R[0];
                            break;
                        }
                        int x=L[u];
                        int y=R[u];
                        R[x]=y;
                        L[y]=x;
                        sum++;
                    }
                }
            }
            else j = nt[j];
        }

        for(int i=R[0];i!=lenp+1;i=R[i])
        {
            printf("%c",p[i]);
        }
        printf("\n");

    }
    return 0;
}