AC题解

#include<bits/stdc++.h>
using namespace std;
int main()
{
    double r,a,b,c;
    cin>>r;
    a=r*2;
    b=2*3.14159*r;
    c=3.14159*r*r;
    printf("%.4f",a);
    cout<<" ";
    printf("%.4f",b);
    cout<<" ";
    printf("%.4f",c);
    return 0;
}

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