Find the Index of the First Occurrence in a String

LeetCode 28. Find the Index of the First Occurrence in a String

원문

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.

풀이

haystack 문자열을 처음부터 순회하며 needle에 해당하는 문자열이 있는지 찾는다.

코드

Python

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

Java

class Solution {
    public int strStr(String haystack, String needle) {
        int idx = 0;
        int n = haystack.length();
        int m = needle.length();

        while (idx <= n - m) {
            for (int i = 0; i < m; i++) {
                if (haystack.charAt(idx + i) != needle.charAt(i)) break;
                if (i == m - 1) return idx;
            }
            idx++;
        }

        return -1;
    }
}