https://leetcode-cn.com/problems/implement-strstr/
class Solution { public int strStr(String haystack, String needle) { if (needle.equals("") || needle==null||needle.equals(haystack)) { return 0 ; } boolean flag=false; for(int i=0;i<haystack.length()-needle.length()+1;i++){ flag=true; for (int j=0;j<needle.length();j++){ if (haystack.charAt(i+j)!=needle.charAt(j)){ flag=false; break; } } if (flag){ return i; } } return -1; } }
