028实现strStr()

#pragma once
#include "000库函数.h"

/*********************自解**************/
//使用算法中的find       12ms
class Solution {
public:
    int strStr(string haystack, string needle) {
        if (haystack.size() == 0 && needle.size() != 0)return -1;
        if (needle.size() == 0)return 0;
        return haystack.find(needle);
    }
};


/********************博客解法*****************/
//使用暴力遍寻法        44ms
class Solution {
public:
    int strStr(string haystack, string needle) {
        if (needle.empty()) return 0;
        int m = haystack.size(), n = needle.size();
        if (m < n) return -1;
        for (int i = 0; i <= m - n; ++i) {
            int j = 0;
            for (j = 0; j < n; ++j) {
                if (haystack[i + j] != needle[j]) break;
            }
            if (j == n) return i;
        }
        return -1;
    }
};

void T028() {
    string haystack, needle;
    haystack = "hello";
    needle = "ll";
    Solution s;
    cout << s.strStr(haystack, needle) << endl;
    haystack = "aaaaa";
    needle = "bba";
    cout << s.strStr(haystack, needle) << endl;
}