Submission #6751675

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Source Code Expand

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
typedef pair<int, int> P;
double cal(int r, int n, int x){
    if(x <= 0 || n <= x)return 0;
    if(x > n/2)return cal(r, n, n-x);
    double y = (double) x * 4 * r / n;
    return sqrt((double)n/x-1) * y;
}
int main(void){
    int r, n, m;
    double ans = 0;
    cin >> r >> n >> m;
    for(int i=1;i<n+m;i++){
        ans += max(cal(r, n, i), cal(r, n, i-m));
    }
    cout << fixed << setprecision(16) << ans << endl;
}

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