_387.java

package com.fishercoder.solutions;

/**
 * 387. First Unique Character in a String
 * 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.
 Note: You may assume the string contain only lowercase letters.

 */

public class _387 {

    public static int firstUniqChar(String s) {
        int[] freq = new int[26];
        for (int i = 0; i < s.length(); i++) {
            freq[s.charAt(i) - 'a']++;
        }
        for (int i = 0; i < s.length(); i++) {
            if (freq[s.charAt(i) - 'a'] == 1) {
                return i;
            }
        }
        return -1;
    }

    public static void main(String... strings) {
        String s = "leetcode";
        System.out.println(firstUniqChar(s));
    }

}