B. Rolling The Polygon(几何+余弦定理)
作者:互联网
B. Rolling The Polygon(几何+余弦定理)
题目链接:https://nanti.jisuanke.com/t/41286
题意:一个n边形内含有一点p,多边形从一条边开始沿其延长线旋转一周,问p的运动长度。
思路:容易推出, p点每一小段的弧长都是一本分圆周运动, 求出多边形每个角的大小和p点距离每个角的距离就能得出答案。
代码:
#include<bits/stdc++.h>
using namespace std;
int x[55];
int y[55];
int xx,yy;
int n,a;
int main()
{
scanf("%d",&a);
for(int p=1;p<=a;p++)
{
scanf("%d",&n);
for ( int i=1; i<=n; i++ ) {
scanf("%d %d",&x[i],&y[i]);
}
x[0] = x[n]; y[0] = y[n];
x[n+1] = x[1]; y[n+1] = y[1];
scanf("%d %d",&xx,&yy);
double ans = 0;
for ( int i=1; i<=n; i++ ) {
double dis = sqrt( (x[i]-xx)*(x[i]-xx) + (y[i]-yy)*(y[i]-yy) );
double cs = 1.0*((x[i-1]-x[i])*(x[i+1]-x[i])+(y[i-1]-y[i])*(y[i+1]-y[i]))/( sqrt((x[i-1]-x[i])*(x[i-1]-x[i])+ (y[i-1]-y[i])*(y[i-1]-y[i]) )*sqrt((x[i+1]-x[i])*(x[i+1]-x[i])+ (y[i+1]-y[i])*(y[i+1]-y[i]) ) );
double o = acos(cs);
ans += (acos(-1)-o)*dis;
}
printf("Case #%d: ",p);
printf("%.3f\n",ans);
}
return 0;
}
标签:多边形,Polygon,int,55,余弦定理,Rolling 来源: https://blog.csdn.net/weixin_43828245/article/details/100176227