题解 | #删除字符串中出现次数最少的字符#

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

// 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();
        String[] s = str.split("");
        StringBuilder sb = new StringBuilder();
        
        //去重str
        for(String c:s){
            int indexOf = sb.indexOf(c);
            if (indexOf==-1){
                sb.append(c);
            }
        }
        
        //记录每个字母出现的次数 并且找到最小值
        Map<String,Integer> map = new HashMap<>();
        for (int i = 0; i < sb.length(); i++) {
            String c = sb.charAt(i)+"";
            int j = str.length()-str.replaceAll(c,"").length();
            map.put(c,j);
        }
        Integer integer = map.values().stream().min(Comparator.comparing(x -> x)).get();
        
        //用“”替换出现次数最少的字母
        for (Map.Entry<String,Integer> entry: map.entrySet()) {
            if (entry.getValue()==integer){
                String key = entry.getKey();
                str = str.replaceAll(key, "");
            }
        }
        System.out.println(str);
    }
}