Problem28.java

class Problem28 {
 public static void main(String[] args) {
 Problem28 p = new Problem28();
 String haystack = "mississippi";
 String needle = "issip";
 System.out.println(p.strStr(haystack, needle));
 }

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