1020 timus Rope

题目大意: 求绳子的长度. 四个转角处的长度正好为一个圆周.

 

#include <iostream> #include <math.h> using namespace std; struct Node { float x; float y; }; float dist(Node a,Node b) { return sqrt(pow(a.x -b.x,2)+pow(a.y -b.y,2)); } int main() { int N,i; float r,sum=0; cin>>N; scanf("%f",&r); sum+= 2*3.14159*r; Node *a = new Node[N]; for ( i=0;i<N;i++) scanf("%f%f",&a[i].x,&a[i].y); for ( i=0;i<N;i++) sum+= dist(a[i],a[(i+1)%N]); printf("%.2f",sum); return 0; }