[LeetCode] Problem 387 - First Unique Character in a String

Posted on | In ,

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

Examples

No.1

s = “leetcode”
return 0.

No.2

s = “loveleetcode”,
return 2.

Note

You may assume the string contain only lowercase letters.

Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
public int firstUniqChar(String s) {
    if (s == null || s.length() < 1)
        return -1;

    int[] index = new int[26];

    for (int i = 0; i < s.length(); i++) {
        int idx = s.charAt(i) - 'a';
        index[idx]++;
    }

    for (int i = 0; i < s.length(); i++) {
        int idx = s.charAt(i) - 'a';

        if (index[idx] == 1)
            return i;
    }

    return -1;
}