题解 | #删除字符串中出现次数最少的字符#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.nextLine();
        System.out.println(solution1(str));
    }

    protected static String solution1(String str) {
        Map<Character, Integer> map = new HashMap<>(str.length());
        for (char c : str.toCharArray()) {
            map.compute(c, (k, v) -> v == null ? 1 : v + 1);
        }
        Integer min = map.values().stream().min(Integer::compare).orElse(0);
        Set<Character> set = new HashSet<>();
        for (Map.Entry<Character, Integer> entry : map.entrySet()) {
            if (entry.getValue().equals(min)) {
                set.add(entry.getKey());
            }
        }
        StringBuilder sb = new StringBuilder();
        for (char c : str.toCharArray()) {
            if (!set.contains(c)) {
                sb.append(c);
            }
        }
        return sb.toString();
    }
}