First Unique Character in a String

LeetCode Q 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.

Solution

Code:

public int firstUniqChar(String s) {
	if (s == null || s.length() == 0) return -1;
	
	int[] count = new int[256];
	for (char ch: s.toCharArray())
		count[ch]++;
	
	for (int i = 0; i < s.length(); i++) {
		if (count[s.charAt(i)] == 1)
			return i;
	}
	
	return -1;
}