题解 | 删除字符串中出现次数最少的字符

import java.util.*;

// 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);
        String string = in.nextLine();
        Map<Character, Integer> map = new HashMap<>();
        for (char c : string.toCharArray()) {
            if (map.containsKey(c)) {
                map.put(c, map.get(c) + 1);
            } else {
                map.put(c, 1);
            }
        }
        List<Map.Entry<Character, Integer>> list = new ArrayList<>(map.entrySet());
        list.sort((o1, o2) -> o1.getValue() - o2.getValue());
        int num = list.get(0).getValue();
        Set<Character> set = new HashSet<>();
        set.add(list.get(0).getKey());
        for (int i = 1; i < list.size(); i++) {
            if (list.get(i).getValue() == num) {
                set.add(list.get(i).getKey());
            } else {
                break;
            }
        }
        StringBuilder sb = new StringBuilder();
        for (char c : string.toCharArray()) {
            if (!set.contains(c)) {
                sb.append(c);
            }
        }
        System.out.println(sb);
    }
}

#牛客春招刷题训练营#

我是先统计每个字符出现的次数，然后找出出现次数最少的字符，然后再将原字符串中不是出现次数最少的字符重新拼接返回