LeetCode 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.

Runtime: 16
ms

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