FirstUniqueCharacterInString

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Examples:

s = "leetcode"
return 0.

s = "loveleetcode"
return 2.

s=""
return -1;

Note:

You may assume the string contain only lowercase letters.

 public class Solution{
     public int firstUniqChar(String s){
         if (s == null || s.equals("")) return -1;
         char[] c = s.toCharArray();
         int[] cnt = new int[256];

         for (int i = 0; i < c.length; i++) {
             cnt[c[i]]++;
             System.out.println(cnt[c[i]]);
         }

         for (int i = 0; i < c.length; i++) {
             if (cnt[c[i]] == 1) return i;
         }
         return -1;
     }
 }