题解 | #删除字符串中出现次数最少的字符#

import java.util.*;
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);
        HashMap<Character,Integer> map=new HashMap<Character,Integer>();
        String s=in.next();
        int len=s.length();
        int min=20;
        for(int i=0;i<len;i++){
            char c=s.charAt(i);
            if(map.containsKey(c)){
                map.put(c,map.get(c)+1);
            }else{
                map.put(c,1);
            }
        }
        TreeSet<Integer> tree=new TreeSet<Integer>();
        for(int n:map.values())tree.add(n);
        min=tree.first();
        StringBuffer sb=new StringBuffer("");
        for(Character c:map.keySet()){
            if(map.get(c)==min)sb.append(c);
        }
        for(int i=0;i<sb.length();i++){
            s=s.replace(Character.toString(sb.charAt(i)),"");
        }
        System.out.print(s);
    }
}