Submission #481471

---

Source Code Expand

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cmath>
#include <cstdlib>
#include <deque>
#include <iostream>
#include <iomanip>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#define rep(i,l) for(int(i)=0; (i)<int(l); i++)
#define mp(x,y) make_pair(x, y)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define pb(x) push_back(x)
#define pob(x) pop_back(x)
#define pf(x) push_front(x)
#define pof(x) pop_front(x)
#define srtg(x) sort(all(x), greater<int>())
#define print(x) cout<<x<<endl;
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef vector<string> vs; typedef vector<double> vd;
typedef pair<int, int> pi;
typedef priority_queue<int> pqi; typedef priority_queue<int, vector<int>, greater<int> > pqig;
typedef vector< vector<int> > vi2;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }


int main() {
	unsigned long long n, k, meddian, p;
	double res;

	cin >> n >> k;
	
	meddian = 1;
	meddian += (n-k)*3;
	meddian += (k-1)*3;
	meddian += (k-1)*(n-k)*6;

	p = pow(n, 3);
	
	res = (double)meddian/p;

	cout << setprecision(10) << res << "\n";

	return 0;
}

Submission Info

Judge Result