28. Implement strStr()

Implement strStr().

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

Example 3:

Input: haystack = "", needle = "" Output: 0

 

Constraints:

• 0 <= haystack.length, needle.length <= 5 * 104
• haystack and needle consist of only lower-case English characters.

• class Solution(object):
      def strStr(self, haystack, needle):
          """
          :type haystack: str
          :type needle: str
          :rtype: int
          """
          if needle == "":
              return 0
          
          try:
              idx = haystack.index(needle, 0, len(haystack))
              return idx
          except ValueError:
              return -1

- 정규식 find/match/search로 풀려고 했으나, string에 좋은 method가 있어서 쉽게 풀었다.