KMP

KMP字符串

//时间复杂度O(n)
#include <iostream>

using namespace std;

const int N = 100010, M = 1000010;

int n, m;
char p[N], s[M];
int ne[N];

int main() {
    cin >> n >> p + 1 >> m >> s + 1;
    
    //求next数组
    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;
    }
    
    //匹配过程
    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) {
            //匹配成功
            printf("%d ", i - n);
            j = ne[j];
        }
    }
    
    return 0;
}

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