一本通1014

//qf
#include <bits/stdc++.h>
#define f(i,j,n) for(register int i=j;i<=n;i++)
using namespace std;
typedef long long ll;
const double p=3.14159;
inline ll read() {
	ll x=0;
	int f=1;
	char ch=getchar();
	while(!isdigit(ch)) {
		if(ch=='-') f=-1;
		ch=getchar();
	}
	while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch-48),ch=getchar();
	return x*f;
}
signed main() {
	double r;
	cin>>r;
	cout<<fixed<<setprecision(4)<<r*2;
	putchar(' ');
	cout<<fixed<<setprecision(4)<<r*2*p;
	putchar(' ');
	cout<<fixed<<setprecision(4)<<r*r*p;
	puts("");
	return 0;
}
不存在十全十美的文章 如同不存在彻头彻尾的绝望
原文地址:https://www.cnblogs.com/qf-breeze/p/10667626.html