题解HJ23 | #删除字符串中出现次数最少的字符#

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.stream.Collectors;

// 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);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String s = in.nextLine();

            String[] split = s.split("");

            List<String> list = Arrays.asList(split);

            Map<String, Long> map = list.stream().collect(Collectors.groupingBy(x -> x,
                                    Collectors.counting()));

            //拿到最小value
            Long min = 20L;

            for (Map.Entry<String, Long> entry : map.entrySet()) {
                if (entry.getValue().compareTo(min) < 0)
                    min = entry.getValue();
            }

            //拿到对应的键
            List<String> arr = new ArrayList();
            for (Map.Entry<String, Long> entry : map.entrySet()) {
                if (min.equals(entry.getValue()))
                    arr.add(entry.getKey());
            }

            for (int i = 0; i < arr.size(); i++) {
                s = s.replace(arr.get(i), "");
            }

            System.out.println(s);
        }
    }
}

最笨的办法