Implement strStr()

Java

class Solution {
		public int strStr(String haystack, String needle) {
      for (int i = 0; ; i++) {
        for (int j = 0; ; j++) {
          if (j == needle.length()) {
              return i;
          }
          if (i + j == haystack.length()) {
              return -1;
          }
          if (needle.charAt(j) != haystack.charAt(i + j)) {
              break;
          }
        }
      }
    }
} 


Time Complexity : O(m*n); length of the string 
Space Complexity : O(1);