【BZOJ 3942】 Censoring

【题目链接】

            https://www.lydsy.com/JudgeOnline/problem.php?id=3942

【算法】

           栈 + KMP

【代码】

          

#include<bits/stdc++.h>
using namespace std;
#define MAXN 1000010

int i,pos,top,ls,lt;
int nxt[MAXN],p[MAXN];
char S[MAXN],T[MAXN],ans[MAXN];
int stk[MAXN];

int main() 
{
        
        scanf("%s%s",S+1,T+1);
        ls = strlen(S+1);
        lt = strlen(T+1);
        for (i = 2; i <= lt; i++)
        {
                pos = nxt[i-1];
                while (pos && T[pos+1] != T[i]) pos = nxt[pos];
                if (T[pos+1] == T[i]) pos++;
                nxt[i] = pos;        
        }
        for (i = 1; i <= ls; i++)
        {
                if (!top)    
                {
                        if (S[i] == T[1]) stk[++top] = 1;
                        else stk[++top] = 0;
                        p[top] = i;
                } else
                {
                        pos = stk[top];
                        while (pos && T[pos+1] != S[i]) pos = nxt[pos];
                        if (T[pos+1] == S[i]) pos++;
                        stk[++top] = pos;
                        p[top] = i;
                        if (pos == lt) top -= lt;
                }
        }
        for (i = 1; i <= top; i++) putchar(S[p[i]]);
        printf("\n");
        
        return 0;
    
}