Submission #187714

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Source Code Expand

#define _CRT_SECURE_NO_WARNINGS
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <iterator>
#include <bitset>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii;
typedef long long ll; typedef vector<long long> vl; typedef pair<long long,long long> pll; typedef vector<pair<long long,long long> > vpll;
typedef vector<string> vs; typedef long double ld;
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 NGs[3];
bool isntNG(int x) {
	rep(i, 3) if(NGs[i] == x) return false;
	return true;
}

vector<vector<double> > nCrd2n;
void nCrd2n_calc(int maxn) {
	nCrd2n.assign(maxn+1, vector<double>(maxn+1, 0));
	nCrd2n[0][0] = 1;
	for(int i = 1; i <= maxn; i ++) {
		nCrd2n[i][0] = nCrd2n[i-1][0] / 2;
		for(int j = 1; j <= i; j ++)
			nCrd2n[i][j] = (nCrd2n[i-1][j-1] + nCrd2n[i-1][j]) / 2;
	}
}

int main() {
	int N, D, X, Y;
	scanf("%d%d%d%d", &N, &D, &X, &Y);
	if(X % D != 0 || Y % D != 0) {
		puts("0");
		return 0;
	}
	X /= D, Y /= D;
	X = abs(X), Y = abs(Y);
	if(X > N || Y > N) {
		puts("0");
		return 0;
	}
	vector<vector<double> > dp(N+1, vector<double>(N * 2 + 1, 0));
	dp[0][0 + N] = 1;
	rep(i, N) rer(j, -i, i) {
		double x = dp[i][j + N];
		if(x < 1e-100) continue;
		dp[i+1][j+1 + N] += x / 2;
		dp[i+1][j-1 + N] += x / 2;
	}
	nCrd2n_calc(N);
	double ans = 0;
	rer(xs, 0, N) {
		int ys = N - xs;
		double p = 1;
		p *= dp[xs][X + N];
		p *= dp[ys][Y + N];
		p *= nCrd2n[N][xs];
		ans += p;
	}
	printf("%.10f\n", ans);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:61:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]

Judge Result