python/TangDou/AcWing/KMP/831_2.cpp

#include <bits/stdc++.h>

using namespace std;
const int N = 100010;
const int M = 1000010;
int n, m, ne[N];
char s[M], p[N];

int main() {
    cin >> n >> (p + 1) >> m >> (s + 1);
    for (int i = 2; i <= n; i++) {
        int j = ne[i - 1]; //其实这是原始版本，代码等价变型后成为了831_1.cpp
        // j的含义:指向当前位置前一位的失配指针位置
        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;
}