1718 Cos的多项式

 1 # include <cstdio>
 2 # include <cstring>
 3 # include <iostream>
 4 # include <algorithm>
 5 # include <cmath>
 6 using namespace std;
 7 # define LL long long
 8 # define INF 0x3f3f3f3f
 9 # define MX 100005
10 /**************************/
11 # define BUF_SIZE 100000
12 # define OUT_SIZE 100000
13 bool IOerror=0;
14 
15 const double pi=acos(-1.0);
16 int main ()
17 {
18     long long n;
19     cin>>n;
20     n%=6;
21     int ans=(int)(2*cos(n*pi/3));
22     cout<<ans<<endl;
23     return 0;
24 }