P4824 [USACO15FEB] Censoring S

原题链接

题解

手写栈存放已经匹配过的位置和每个位置匹配的进度，每次匹配成功就回溯，相当于删除子串

code

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

int con[1000006],pre[1000006]={0},st[1000006]={0};
void solve()
{
    string s1,s2;
    cin>>s1>>s2;

    int n=s1.size();
    int len=s2.size();


    s1=' '+s1;
    s2=' '+s2;
    int it=0;
    for(int i=2;s2[i];i++)
    {
        while(it&&s2[it+1]!=s2[i]) it=pre[it];

        if(s2[it+1]==s2[i]) it++;
        pre[i]=it;
    }

    //for(int i=1;i<=len;i++) cout<<pre[i]<<' ';cout<<'\n';

    int top=1;
    it=0;
    for(int i=1;s1[i];i++)
    {
        while(it&&s2[it+1]!=s1[i]) it=pre[it];

        if(s2[it+1]==s1[i]) it++;

        //printf("top:%d  it:%d\n",top,it);
        con[i]=it;
        if(con[i]==len)
        {
            top-=len;
            it=con[st[top]];
            top++;
        }
        else st[top++]=i;
    }

    for(int i=1;i<top;i++) cout<<s1[st[i]];
}
int main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int t=1;
    //cin>>t;
    while(t--) solve();
    return 0;
}