Submission #259383

---

Source Code Expand

#include <bits/stdc++.h>
#include <sys/time.h>
#include <unistd.h>
using namespace std;
#define i64         int64_t
#define rep(i, n)   for(i64 i = 0; i < ((i64)(n)); ++i)
#define sz(v)       ((i64)((v).size()))
#define bit(n)      (((i64)1)<<((i64)(n)))
#define all(v)      (v).begin(), (v).end()

template <int POS, class TUPLE> void deploy(std::ostream &os, const TUPLE &tuple){}
template <int POS, class TUPLE, class H, class ...Ts> void deploy(std::ostream &os, const TUPLE &t){ os << (POS == 0 ? "" : ", ") << get<POS>(t); deploy<POS + 1, TUPLE, Ts...>(os, t); }
template <class ...Ts> std::ostream& operator<<(std::ostream &os, const std::tuple<Ts...> &t){ os << "("; deploy<0, std::tuple<Ts...>, Ts...>(os, t); os << ")"; return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::vector<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "" : ", "); os << "}"; return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::set<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "" : ", "); os << "}"; return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::queue<T> &q){ auto qq = q; os << "{"; for(; !qq.empty(); qq.pop()){ os << qq.front() << (qq.size() != 1 ? ", " : ""); } os << "}"; return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::priority_queue<T> &q){ auto qq = q; os << "{"; for(; !qq.empty(); qq.pop()){ os << qq.top() << (qq.size() != 1 ? ", " : ""); } os << "}"; return os; }
template <class T, class K> std::ostream& operator<<(std::ostream &os, std::pair<T, K> &p){ os << "(" << p.first << ", " << p.second << ")"; return os; }
template <class T, class K> std::ostream& operator<<(std::ostream &os, std::map<T, K> &mp){ int remain = mp.size(); os << "{"; for(auto e: mp) os << "(" << e.first << " -> " << e.second << ")" << (--remain == 0 ? "" : ", "); os << "}"; return os; }
template <class T, class K> std::ostream& operator<<(std::ostream &os, std::unordered_map<T, K> &mp){ int remain = mp.size(); os << "{"; for(auto e: mp) os << "(" << e.first << " -> " << e.second << ")" << (--remain == 0 ? "" : ", "); os << "}"; return os; }
#define DEBUG0() { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << std::endl; }
#define DEBUG1(var0) { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << (#var0) << "=" << (var0) << std::endl; }
#define DEBUG2(var0, var1) { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << (#var0) << "=" << (var0) << ", " << (#var1) << "=" << (var1) << std::endl; }
#define DEBUG3(var0, var1, var2) { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << (#var0) << "=" << (var0) << ", " << (#var1) << "=" << (var1) << ", " << (#var2) << "=" << (var2) << std::endl; }
#define DEBUG4(var0, var1, var2, var3) { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << (#var0) << "=" << (var0) << ", " << (#var1) << "=" << (var1) << ", " << (#var2) << "=" << (var2) << ", " << (#var3) << "=" << (var3) << std::endl; }
#define DEBUG5(var0, var1, var2, var3, var4) { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << (#var0) << "=" << (var0) << ", " << (#var1) << "=" << (var1) << ", " << (#var2) << "=" << (var2) << ", " << (#var3) << "=" << (var3) << ", " << (#var4) << "=" << (var4) << std::endl; }
#define DEBUG6(var0, var1, var2, var3, var4, var5) { char buf[1000]; sprintf(buf, "line:%3d | ", __LINE__); std::cout << buf << (#var0) << "=" << (var0) << ", " << (#var1) << "=" << (var1) << ", " << (#var2) << "=" << (var2) << ", " << (#var3) << "=" << (var3) << ", " << (#var4) << "=" << (var4) << ", " << (#var5) << "=" << (var5) << std::endl; }
#define ASSERT(f) { if(!(f)){ DEBUG1("error"); while(true); }}



const i64 MAX = 1050;
double dp[MAX][MAX];
double cal(i64 n, i64 m)
{
  if(m < 0 || n < m) return 0.0;
  if(n == 0) return 1.0;
  double &res = dp[n][m];
  if(res != -1) return res;
  res = (cal(n - 1, m) + cal(n - 1, m - 1)) * 0.5;
  return res;
}

double cal2(i64 m, i64 n)
{
  if(n < m) return 0.0;
  if((n - m) % 2) return 0.0;
  return cal(n, (n - m) / 2);
}

int main()
{
  i64 n, d, x, y;
  while(cin >> n >> d >> x >> y){
    rep(i, MAX)rep(j, MAX) dp[i][j] = -1;

    if(abs(x) % d != 0 && abs(y) % d != 0){
      cout << 0 << endl;
    }else{
      double ans = 0.0;
      for(i64 vertical = 0; vertical <= n; ++vertical){
	double p = cal(n, vertical);
	ans += p * cal2(abs(x) / d, vertical) * cal2(abs(y) / d, (n - vertical));
      }
      printf("%0.20lf\n", ans);
    }

  }
}

Submission Info

Judge Result