[sword finger offer] 50 First character that appears only once

The finger of the sword Offer 50. The first character that appears only once

subject

  In string s Find the first character that appears only once . without , Return a single space . s Contains only lowercase letters .

Ideas

  Create a new hash table , Store... As a key value pair , value - The number of occurrences of each character （ Boolean type ）, Finally, the loop returns the first character that appears only once .

Code

class Solution {
    
    public char firstUniqChar(String s) {
    
        HashMap<Character,Boolean> dic = new HashMap<>();
        char[] sc = s.toCharArray();

        for(char c : sc)
        {
    
            dic.put(c,!dic.containsKey(c));//  If it is not in the Kazakhstan table   Add it directly 
        }

        for(char  c:sc)
        {
    
            if(dic.get(c))
            {
    
                return c;//  Get the first occurrence of the character  
            }
        }
        return ' ';//  If not, return a space 
    }
}