leetcode学习笔记42

28. Implement strStr()

Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Example 1:

Input: haystack = “hello”, needle = “ll”
Output: 2
Example 2:

Input: haystack = “aaaaa”, needle = “bba”
Output: -1

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