题解 | #字符集合#

public class Main{
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNextLine()) {
        String str = scanner.nextLine();
        HashMap<Character, Integer> hashtable = new HashMap<Character,Integer>();
        for(int i = 0;i<str.length();i++) {
            if(!hashtable.containsKey(str.charAt(i))){
                System.out.print(str.charAt(i));
                hashtable.put(str.charAt(i),i);
            }
        }
            System.out.println();
    }
} 
}

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