题解 | #删除字符串中出现次数最少的字符#

char + "" ---> String

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 str = in.nextLine();

        Map<Character, Integer> map = new HashMap<>();
        List<Integer> list = new ArrayList<>();
        StringBuffer sb = new StringBuffer();

        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if (map.get(ch) == null) {
                map.put(ch, 1);
            } else {
                map.put(ch, map.get(ch) + 1);
            }
        }

        for (Map.Entry<Character, Integer> entry : map.entrySet()) {
            list.add(entry.getValue());
        }

        //获取出现最小的次数
        Integer min = Collections.min(list);

        //获取最小次数的字符集
        for (Map.Entry<Character, Integer> entry : map.entrySet()) {
            if (entry.getValue() == min) {
                sb.append(entry.getKey());
            }
        }
        String minStr = sb.toString();
        //删除
        for (int i = 0; i < minStr.length(); i++) {
            str = str.replace(minStr.charAt(i) + "", "");
        }

        System.out.println(str);
    }

}