leetcode28

public class Solution {
    public int StrStr(string haystack, string needle) {
        return haystack.IndexOf(needle);
    }
}

https://leetcode.com/problems/implement-strstr/#/description

python实现，不实用内置函数：

 class Solution:
     def strStr(self, haystack: str, needle: str) -> int:
         n = len(haystack)
         m = len(needle)
         if m == :
             return
         if n ==  or m > n:
             return -
         if haystack == needle:
             return 

         i,j = ,
         idx = i
         while i < n and j < m:
             if haystack[i] != needle[j]:
                 i = idx +
                 idx = i
                 j =
             else:
                 if idx == -:
                     idx = i
                 i +=
                 j +=
             if j == m:
                 return idx
         return -

作为一道easy题目，提交成功率只有33%，可以看出本题的一些细节需要仔细分析，否则很容易出错。