50道编程题之09:一个数如果刚好等于它的因子之和，这个数就称为“完数”。例如6 = 1+2+3，编程实现求[a,b]之间的所有完数

package com.demo;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.*;

public class Demo9 {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

String str = br.readLine();

String[] split = str.split(" ");

int a = Integer.parseInt(split[0]);

int b = Integer.parseInt(split[1]);

for (int i = a ; i <= b ; i ++) {

HashSet<Integer> set = new HashSet<>();

for (int j = 1 ; j < i ; j ++) {

if (i % j == 0) {

set.add(j);

}

}

int sum = 0;

for (Integer ii : set) {

sum += ii;

}

if (sum == i) {

System.out.println(i);

}

}

}

}