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28. Find The Index Of The First Occurrence In A String

Two Pointers String String Matching

Problem - Find The Index Of The First Occurrence In A String

Easy

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.

 

Example 1:

Input: haystack = "sadbutsad", needle = "sad"
Output: 0
Explanation: "sad" occurs at index 0 and 6.
The first occurrence is at index 0, so we return 0.

Example 2:

Input: haystack = "leetcode", needle = "leeto"
Output: -1
Explanation: "leeto" did not occur in "leetcode", so we return -1.

 

Constraints:

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

Solutions

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class Solution:
    def strStr(self, haystack: str, needle: str) -> int:
        n, m = len(haystack), len(needle)
        for i in range(n - m + 1):
            if haystack[i:i + m] == needle:
                return i
        return -1

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 17.9 MB (10.45%)