OJ---删除字符串中出现次数最少的字符

一开始想用arr[128]对应各个字符，数组的值就是出现次数。发现实现char字符与arr[i]对应很麻烦，参考了别人的思路就换成HashMap实现。

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNext()) {
            String str = in.nextLine();
            Map<Character, Integer> map = new HashMap<>();
            for (char ch : str.toCharArray()) {
                map.put(ch, map.getOrDefault(ch, 0) + 1);
            }
            int min = Integer.MAX_VALUE;
            for (int i : map.values()) {
                min = Math.min(min, i);
            }
            StringBuilder builder = new StringBuilder();
            for (char ch : str.toCharArray()) {
                if (min != map.get(ch)) {
                    builder.append(ch);
                }
            }
            System.out.println(builder.toString());
        }
    }
}