【USACO15Feb】审查

题面

https://www.luogu.org/problem/P3121

题解

// luogu-judger-enable-o2
#include<cstdio>
#include<iostream>
#include<cstring>
#include<queue>
#define ri register int
#define N 100050
using namespace std;

char t[N];
char s[N];
int n;

struct acautomato{
  int ch[N][26];
  int nex[N],cnt[N],last[N];
  int tot;
  int pre[N];
  char ans[N];
  int ton[N],book[N];
  void insert() {
    int now=0;
    int l=strlen(s+1);
    for (ri i=1;i<=l;i++) {
      int c=s[i]-'a';
      if (!ch[now][c]) ch[now][c]=++tot;
      now=ch[now][c];
    }
    cnt[now]=l;
  }
  void getfail() {
    queue<int> q;
    while (!q.empty()) q.pop();
    for (ri c=0;c<26;c++) if (ch[0][c]) {
      if (cnt[ch[0][c]]) last[ch[0][c]]=cnt[ch[0][c]]; else last[ch[0][c]]=0;
      q.push(ch[0][c]);
    }
    while (!q.empty()) {
      int x=q.front(); q.pop();
      for (ri c=0;c<26;c++) {
        int y=ch[x][c];
        if (!y) ch[x][c]=ch[nex[x]][c]; 
        else {
          nex[y]=ch[nex[x]][c];
          if (cnt[y]) last[y]=cnt[y]; else last[y]=last[nex[y]];
          q.push(y);
        }
      }
    }
  }
  void dp() {
    int now=0;
    int l=strlen(t+1);
    for (ri i=1;i<=l+1;i++) pre[i]=i-1;
    for (ri i=1;i<=l;i++) {
      now=ch[now][t[i]-'a'];
      book[i]=now;
      if (last[now]) {
        int j=i,ll=1;
        while (ll<last[now]) j=pre[j],ll++;
        pre[i+1]=pre[j];
        now=book[pre[j]];
      }
    }
    int p=pre[l+1],cnt=0;
    while (p) {
      ans[++cnt]=t[p];
      p=pre[p];
    }
    for (ri i=cnt;i>=1;i--) cout<<ans[i];
    cout<<endl;
  }
} trie;

int main(){
  scanf("%s",t+1);
  scanf("%d",&n);
  for (ri i=1;i<=n;i++) {
    scanf("%s",s+1);
    trie.insert();
  }
  trie.getfail();
  trie.dp();
}