28. Implement strStr()

class Solution {
    public int strStr(String haystack, String needle) {
        if (needle.equals("")) {
            return 0;
        }
        
        if (haystack.length() < needle.length()) {
            return -1; 
        }
        
        char cur = needle.charAt(0); 
        int loc = 0;
        int needleL = needle.length() - 1;
        
        for (int i = 0; i < haystack.length() - needleL; i++) {
            if (haystack.charAt(i) == cur) {
                if (haystack.substring(i, i + needleL + 1).equals(needle)) {
                    return i;
                }
            }
        }
        
        return -1; 
    }
}

Runtime: 0 ms, faster than 100.00% of Java online submissions for Implement strStr().
Memory Usage: 38.8 MB, less than 38.46% of Java online submissions for Implement strStr().

쉬운데.... 꽃남보느라 300년걸림 ㅠ