下标从0开始的kmp匹配

C++ 代码

class Solution {
public:
    int strStr(string h, string p) {
        if (p.empty()) return 0;
        int n = h.length(), m = p.length();
        vector<int> ne(m);
        ne[0] = -1;
        for (int i = 1, j = -1; i < m; i++) 
        {
            while (j > -1 && p[i] != p[j + 1]) j = ne[j];
            if (p[i] == p[j + 1]) j++;
            ne[i] = j;
        }
        for (int i = 0,j = -1; i < n; i++) 
        {
            while (j > -1 && h[i] != p[j + 1]) j = ne[j];
            if (h[i] == p[j + 1]) j++;
            if (j == m - 1)
                return i - m + 1;
        }
        return -1;

    }
};