题解 | #删除字符串中出现次数最少的字符#

import java.util.*;
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
            System.out.println(deleteFewestChar(in.nextLine()));
        }
    }

    
    /**
     * HJ23 删除字符串中出现次数最少的字符
     */
    private static String deleteFewestChar(String str) {
        Map<Character, Integer> charMap = new HashMap<>(26);
        char[] arr = str.toCharArray();
        for (char c : arr) {
            charMap.compute(c, (k, v) -> v == null ? 1 : v + 1);
        }
        int min = Collections.min(charMap.values());
        String ss = charMap.entrySet().stream().
                filter(entry -> entry.getValue() == min).map(Map.Entry::getKey).map(String::valueOf).collect(Collectors.joining());
        return str.replaceAll("[" + ss + "]","");
    }

}