题解 | #字符串排序#

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 sentence = in.nextLine();
        char[] charArr = sentence.toCharArray();
        bubbleSort(charArr);
        for (char c : charArr) {
            System.out.print(c);
        }
    }

    private static void bubbleSort(char[] arr) {
        for (int i = 0; i < arr.length; i++) {
            int j = 0;
            int k = 1;
            while (k < arr.length - i) {
                if (!Character.isLetter(arr[j])) {
                    j = k;
                    k = j + 1;
                    continue;
                }

                if (!Character.isLetter(arr[k])) {
                    k++;
                    continue;
                }

                if (Character.toLowerCase(arr[j]) > Character.toLowerCase(arr[k])) {
                    char tmp = arr[j];
                    arr[j] = arr[k];
                    arr[k] = tmp;
                }
                j = k;
                k = j + 1;
            }
        }
    }
}