AcWing 831. KMP字符串

#include <iostream>
#include<cstring>
#include<algorithm>
 
using namespace std ;
const int N = 1e6 +10 ;
char s[N] , p[N] ;
int n , m ;
int ne[N] ;
int main(){
  cin >> n >> p + 1  >> m >> s + 1 ;
  for(int i = 2, j = 0 ; i <= n ; i ++){
    while(j && p[i] != p[j+1]) j = ne[j] ;
    if(p[i] == p[j+1]) j ++ ;
    ne[i] = j ;
  }  
  for(int i = 1,j = 0 ; i <= m ; i ++){
    while(j && s[i] != p[j+1]) j = ne[j] ;
    if(s[i] == p[j+1]) j ++ ;
    if(j == n ){
      printf("%d ", i - n) ; 
      j = ne[j] ;
    }
  }
  
  return 0 ;
}