28. Implement strStr()

Easy


Implement strStr().

Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Clarification:

What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().

 

Example 1:

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"
Output: -1

 

Constraints:

  • 1 <= haystack.length, needle.length <= 104
  • haystack and needle consist of only lowercase English characters.




 class Solution:
    def strStr(self, haystack: str, needle: str) -> int:

        return haystack.find(needle)

Random Note


Substring a String

  • string[start:end:step]
  • from first string[2:6]
  • last char string[-1]
  • last char by index string[-1]
  • from last string[-5:]
  • first to last string[1:-4]