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() ==  && needle.size() != )return -;
         if (needle.size() == )return ;
         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 ;
         int m = haystack.size(), n = needle.size();
         if (m < n) return -;
         for (int i = ; i <= m - n; ++i) {
             int j = ;
             for (j = ; j < n; ++j) {
                 if (haystack[i + j] != needle[j]) break;
             }
             if (j == n) return i;
         }
         return -;
     }
 };

 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;
 }