Blue Bridge Cup - 2012b Group real question 3 specific drinking capacity

Title Description
There's a group of pirates （ Not more than 20 people ）, Compete for alcohol on board . The process is as follows ： Open a bottle of wine , Everyone present shared the drink equally , Several people fell down . Open another bottle and divide it equally , There's another one down , Repeat... Again ---- Until the second time 4 A bottle of wine , There is little left to sit , The pirate captain is among them . When the first 4 After a bottle of wine is divided equally , Everyone fell . When the captain wakes up , The pirate ship was found stranded . He wrote in the log that ：“… yesterday , I just drank a bottle … I advise you to , Sailing without drinking , Drink and don't sail …”
Please use this information , Infer how many people started , How many people are left after each round of drinking . If there are multiple possible answers , Please list all the answers , Each answer takes up one line . The format is ： The number of , The number of ,…
for example , One possibility is ：20,5,4,2,0

The code is as follows

#include<iostream>
#include<cmath>
using namespace std;
int main()
{
    
	// Here the violent solution is used  
	for(int n1=20;n1>4;n1--){
        // There must be at least four people in the first round , To finish four rounds  
		for(int n2=n1-1;n2>3;n2--){
      // Every round someone fell , So at least one person fell  
			for(int n3=n2-1;n3>2;n3--){
    
				for(int n4=n3-1;n4>1;n4--){
    
					if(fabs((1.0/n1+1.0/n2+1.0/n3+1.0/n4)-1)<=1e-5){
      // Except integer zero , Floating point numbers are imprecise when they represent zero , It is not accurate from the decimal place , So it depends on whether this number is small enough , To a certain extent, it can be regarded as 0 了  
						cout<<n1<<" "<<n2<<" "<<n3<<" "<<n4<<" 0"<<endl;
					}
				}
			}
		}
	}
	return 0;
}