387. First Unique Character in a String

Description

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

Note: You may assume the string contains only lowercase English letters.

Constraints

Approach

Links

• GeeksforGeeks

• Leetcode

• ProgramCreek

• YouTube

Examples

Example 1

Input: s = "leetcode"

Output: 0

Example 2

Input: s = "loveleetcode"

Output: 2

Solutions

Solution 1

/**
 * Time complexity : 
 * Space complexity : 
 */

class Solution {
    public int firstUniqChar(String s) {
        if(s != null && s.length() != 0) {
            int[] count = new int[26];
            for(char ch: s.toCharArray()) {
                count[ch-'a']++;
            }
            for(int i = 0; i < s.length(); i++) {
                if(count[s.charAt(i)-'a'] == 1) {
                    return i;
                }
            }
        }
        return -1;
    }
}

Follow up