public class Solution {

public int strStr(String haystack, String needle) {

int needleLen = needle.length();

int haystackLen = haystack.length();

if (needleLen == 0) return 0;

if (haystackLen == 0) return -1;

for (int i = 0; i <= haystackLen - needleLen; i++) {

int k = i, j = 0;

while (j < needleLen && k < haystackLen && needle.charAt(j) == haystack.charAt(k)) {

j++;

k++;

if (j == needleLen) return i;

}

}

return -1;

}

public static void main(String[] args) {

Solution s = new Solution();

System.out.println(s.strStr("helllo", "ll"));

}

}