ural 1246. Tethered Dog
5464 ワード
http://acm.timus.ru/problem.aspx?space=1&num=1246
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1 #include <cstdio>
2 #include <cstring>
3 #include <algorithm>
4 #define maxn 200010
5 using namespace std;
6
7 struct node
8 {
9 double x,y;
10 }p[maxn];
11
12 double cross(node a,node b,node c)
13 {
14 return (c.x-a.x)*(b.y-a.y)-(c.y-a.y)*(b.x-a.x);
15 }
16
17 int main()
18 {
19 int n;
20 scanf("%d",&n);
21 for(int i=1; i<=n; i++)
22 {
23 scanf("%lf%lf",&p[i].x,&p[i].y);
24 }
25 p[n+1]=p[1]; p[0]=p[n];
26 int c=0;
27 for(int i=1; i<=n; i++)
28 {
29 if(p[i].x>p[c].x)
30 {
31 c=i;
32 }
33 }
34 if(c==0) c=n;
35 if(cross(p[c-1],p[c],p[c+1])>=0) printf("cw
");
36 else printf("ccw
");
37 return 0;
38 }
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