Submission #187860

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Source Code Expand

#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <cstring>
#include <string>
#include <cstdlib>
#include <cstdio>
using namespace std;
typedef pair<int, int> pii;
typedef long long int ll;
#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define RREP(i,x) for(int i=(x);i>=0;i--)
#define RFOR(i,c) for(__typeof((c).rbegin())i=(c).rbegin();i!=(c).rend();++i)


ll N, D, X, Y;

double dp[2][205][205];

int d[4][2]={{0,1},{1,0},{0,-1},{-1,0}};

main(){
	cin >> N >> D >> X >> Y;
	if(X%D || Y%D){
		cout << 0 << endl;
		return 0;
	}
	X /= D;
	Y /= D;
	if(abs(X) > 100 || abs(Y) > 100){
		cout << 0 << endl;
		return 0;
	}
	dp[0][100][100] = 1.0;
	REP(i, N){
		for(int x=-99;x<=99;x++)for(int y=-99;y<=99;y++){
			REP(k, 4){
				int dx = x+d[k][0];
				int dy = y+d[k][1];
				dp[1^i&1][dx+100][dy+100] += dp[1&i][x+100][y+100]*0.25;
			}
			dp[1&i][x+100][y+100] = 0;
		}
	}
	printf("%.11f\n", dp[N&1][X+100][Y+100]);
}

Submission Info

Judge Result