题解 | #删除字符串中出现次数最少的字符#

import java.util.*;
import java.io.*;

// 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) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        String line;
        while((line=br.readLine())!= null) {
            HashMap<Character, Integer> counter = new HashMap<>();
            for (int i = 0; i < line.length(); ++i) {
                counter.merge(line.charAt(i), 1, Integer::sum);
            }
            
            int min = Collections.min(counter.values());
            
            for (int i = 0; i < line.length(); ++i) {
                char target = line.charAt(i);
                if (counter.get(target) != min) {
                    bw.write(target);
                }
            }
            bw.newLine();
        }
        bw.close();
        br.close();
    }
}