CodeForces 305B Continued Fractions【递推的分式】

今天下午把最近一段时间CF做过的题整理下

先说着今天做的两个侮辱智商的题==

Description

A continued fraction of height n is a fraction of form 

. You are
given two rational numbers, one is represented as 

 and the other one is represented as a finite fraction of height n.
Check if they are equal.

Input

The first line contains two space-separated integers p, q(1 ≤ q ≤ p ≤ 1018) —
the numerator and the denominator of the first fraction.

The second line contains integer n(1 ≤ n ≤ 90) — the height of the second fraction. The third line contains n space-separated
integersa1, a2, ..., an(1 ≤ ai ≤ 1018) —
the continued fraction.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64dspecifier.

Output

Print "YES" if these fractions are equal and "NO" otherwise.

Sample Input

Input

9 4
2
2 4

Output

YES

Input

9 4
3
2 3 1

Output

YES

Input

9 4
3
1 2 4

Output

NO

Hint

In the first sample 

.

In the second sample 

.

In the third sample 

.

一开始觉得既然是B题，小case啊，浮点数挨个除吧，然而浮点数相除一定会出现问题！本题正误而的解法是把每次读入的a移到等式左边，如果读入的a大于左边的式子或者没结束就出现了有一项等于0，那么一定输出no

#include <iostream>
using namespace std;
long long n,p,q,a;
int main()
{
//freopen("cin.txt","r",stdin);

cin>>p>>q>>n;
while(n)
{
cin>>a;
if(q==0||a>(p/q)) break;
long long t=q;
q=p-a*q;
p=t;
n--;
}
if(n||q) cout<<"NO"<<endl;
else cout<<"YES"<<endl;

return 0;
}


这几天选择语言的时候都默认是php ，今天居然变成html了，这是提示我该学那些了吗……