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 line = in.nextLine();

        Map<Character, Integer> map = new HashMap<>();
        // 先统计各个字符的频次
        for (int i = 0; i < line.length(); i++) {
            char ch = line.charAt(i);
            map.put(ch, map.getOrDefault(ch, 0) + 1);
        }

        // 找出最小频次
        int min = line.charAt(0);
        for (int val : map.values()) {
            min = Math.min(min, val);
        }

        // 如果该字符出现频次最少，则跳过字符串拼接
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < line.length(); i++) {
            char ch = line.charAt(i);
            if (map.get(ch).equals(min)) continue;

            sb.append(ch);
        }

        System.out.println(sb.toString());
    }
}