题解 | #删除字符串中出现次数最少的字符#

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;

public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while(sc.hasNext()) {

String str =sc.nextLine();
String[] array = str.split("");
Map<String,Integer> map = new HashMap<>();
for (int i = 0; i < array.length; i++) {
    String string = array[i];
    if(map.containsKey(string)) {
        map.put(string, map.get(string)+1);
    }else {
        map.put(string, 1);
    }

}
List<Map.Entry<String, Integer>> ls = new ArrayList<>(map.entrySet());
Collections.sort(ls,new Comparator<Map.Entry<String, Integer>>() {
    @Override
    public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
        return o1.getValue().compareTo(o2.getValue());
    }
});
int m=ls.get(0).getValue();

for(Map.Entry<String, Integer> ma:ls) {
if(ma.getValue()>m) {
break;
}else {
str = str.replaceAll(ma.getKey(), "");
}
}
System.out.println(str);
}
}}