Implement the strStr() function.
Given a haystack string and a needle string, find the first position (0-based) in the haystack string where the needle string occurs. Returns -1 if not present .
Example 1:
Input: haystack = "hello", needle = "ll" Output: 2
Example 2:
Input: haystack = "aaaaa", needle = "bba" Output: -1
python code
class Solution: def strStr(self, haystack, needle): """ :type haystack: str :type needle: str :rtype: int """ len1 = len (haystack) len2=len(needle) for i in range(len1-len2+1): if haystack[i:i+len2]==needle: return i return -1