Find the Index of the First Occurrence in a String
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 <= 10^4
haystack and needle consist of only lowercase English characters.
My Solution
This is a one-liner in Java using the indexOf function of the String class.
The time complexity of the indexOf function is O(m*n), where m is the length of haystack and n is the length of needle.
class Solution {
public int strStr(String haystack, String needle) {
return haystack.indexOf(needle);
}
}