028实现strStr()

 1 #pragma once
 2 #include "000库函数.h"
 3 
 4 /*********************自解**************/
 5 //使用算法中的find       12ms
 6 class Solution {
 7 public:
 8     int strStr(string haystack, string needle) {
 9         if (haystack.size() == 0 && needle.size() != 0)return -1;
10         if (needle.size() == 0)return 0;
11         return haystack.find(needle);
12     }
13 };
14 
15 
16 /********************博客解法*****************/
17 //使用暴力遍寻法        44ms
18 class Solution {
19 public:
20     int strStr(string haystack, string needle) {
21         if (needle.empty()) return 0;
22         int m = haystack.size(), n = needle.size();
23         if (m < n) return -1;
24         for (int i = 0; i <= m - n; ++i) {
25             int j = 0;
26             for (j = 0; j < n; ++j) {
27                 if (haystack[i + j] != needle[j]) break;
28             }
29             if (j == n) return i;
30         }
31         return -1;
32     }
33 };
34 
35 void T028() {
36     string haystack, needle;
37     haystack = "hello";
38     needle = "ll";
39     Solution s;
40     cout << s.strStr(haystack, needle) << endl;
41     haystack = "aaaaa";
42     needle = "bba";
43     cout << s.strStr(haystack, needle) << endl;
44 }