UVa12970

解題心得

表面上看起來很容易，但牽扯到數字約分就比較複雜。

要記得gcd怎麼寫。

程式碼

#include <iostream>
using namespace std;

long long int gcd(long long int a, long long int b)
{
	while((a%=b)!=0 && (b%=a)!=0);
	return a+b;
}
int main()
{
	int count=1;
	long long int v1, d1, v2, d2;
	while(cin>>v1>>d1>>v2>>d2)
	{
		if(v1==0 && d1==0 && v2==0 && d2==0) break;
		
		cout<<"Case #"<<count++<<": ";
		if(float(d1)/v1 < float(d2)/v2)
			cout<<"You owe me a beer!"<<endl;
		else
			cout<<"No beer for the captain."<<endl;
			
		cout<<"Avg. arrival time: ";
		long long int up, down,_gcd;
		up=d1*v2 + d2*v1;
		down=2*v1*v2;
		_gcd=gcd(up,down);
		
		up/=_gcd, down/=_gcd;
		if(down==1)
			cout<<up<<endl;
		else
			cout<<up<<"/"<<down<<endl;
	}
	return 0;
}