1 题目

2 代码

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class B1043 {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        char[] ch = br.readLine().toCharArray();

        char[] hash = new char[123];
        for (int i = 0; i < ch.length; i++) {
            hash[ch[i]]++;
        }

        int num = hash['P'] + hash['A'] + hash['T'] + hash['e'] + hash['s'] + hash['t'];
        while (num != 0) {
            if (hash['P'] != 0) {
                hash['P']--;
                System.out.print("P");
                num--;
            }
            if (hash['A'] != 0) {
                hash['A']--;
                System.out.print("A");
                num--;
            }
            if (hash['T'] != 0) {
                hash['T']--;
                System.out.print("T");
                num--;
            }
            if (hash['e'] != 0) {
                hash['e']--;
                System.out.print("e");
                num--;
            }
            if (hash['s'] != 0) {
                hash['s']--;
                System.out.print("s");
                num--;
            }
            if (hash['t'] != 0) {
                hash['t']--;
                System.out.print("t");
                num--;
            }
        }
    }
}

3 要点

（1）利用Hash表就OK了。