/*
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) {
for( int i = 0; i <= haystack.length()-needle.length(); i++) {
if(haystack.substring(i,i + needle.length()).equals(needle))
return i;
}
return -1;
}
}
// substring的用法+遍历