【POJ3461】Oulipo

题面

https://vjudge.net/problem/POJ-3461

题解

#include<cstdio>
#include<iostream>
#include<cstring>
#define ri register int
#define N 1000500
using namespace std;
int T,next[N],n,m;
char s[N],t[N];

void getnext(){
  next[0]=next[1]=0;
  for (ri i=2;i<=n;i++) {
    int j=next[i-1];
    while (j && s[j+1]!=s[i]) j=next[j];
    if (s[j+1]==s[i]) next[i]=j+1; else next[i]=0;
  }
}

int main(){
  scanf("%d",&T);
  while (T--) {
    scanf("%s",s+1); n=strlen(s+1);
    scanf("%s",t+1); m=strlen(t+1);
    getnext();
    int k=0;
    int sum=0;
    for (ri i=1;i<=m;i++) {
      while (k && s[k+1]!=t[i]) k=next[k];
      if (s[k+1]==t[i]) {
        k++;
        if (k==n) {
          k=next[k];
          sum++;
        }
      }
    }
    printf("%d\n",sum);
  }
  return 0;
}