Blue Bridge Cup - microbial appreciation

Microbial appreciation

topic

Suppose there are two microorganisms X and Y, X birth 3 minutes after divided once (double the number) intervals, Y 2 minutes divided once (double the number) intervals after birth.
A new-born X, half a minute after eating a Y, and, from the beginning, every minute to eat a Y.
Now give a constant n (n <= 60 and n is an integer) allows you to calculate the number y after n minutes.

Entry

The first input line n, x, y

10 2 20

Export

If y is the number of y <= 0 then outputs the output y n = 0 minutes

240

Thinking

The treated as a unit of half a minute, then split x: time% 6 == 0; y split: time% 4 == 0; x eat y: x% 2 == 1

Code

#include<iostream>
using namespace std;  

int main()
{
	int n,a,b;
	cin>>n>>a>>b;
	for(int i=1;i<=n;i++)
	{
		if(i%2==1) b=b-a;
		if(b<0) 
		{
			b=0;
			break;
		}
		if(i%6==0) a *= 2;
		if(i%4==0) b *= 2; 
	}
	cout<<b;
	return 0;
}