题解 | #图片整理#

Hash思想

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.nextLine();
        // 前提知道： ascii码表 0-9 -> A-Z -> a-z
        int[] seat = new int['z' + 1];
        for (int i = 0; i < str.length(); i++) {
            int temp = str.charAt(i);
            seat[temp] = seat[temp] + 1;
        }
        for (int i = '0'; i <= 'z'; i++) {
            while (seat[i] > 0) {
                seat[i] = seat[i] - 1;
                System.out.print((char)i);
            }
        }


    }
}