28. 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.

Solution

My Solution

func strStr(haystack string, needle string) int {

    if len(haystack) < len(needle) {
        return -1
    }

    for i := 0; i < len(haystack); i++ {
        if haystack[i] == needle[0] {
            if len(haystack)-i < len(needle) {
                return -1
            }
            if haystack[i:i+len(needle)] == needle {
                return i
            }
        }
    }

    return -1
}

result

Leetcode: link