Submission #1034511

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,a) FOR(i,0,a)
typedef long long ll;

const int MAX_N=100;

int N;

double fact[MAX_N+1],p3[MAX_N+1],dp[MAX_N+1];

double C(int n,int k){
	return fact[n]/fact[n-k]/fact[k];
}

int main(){
	scanf("%d",&N);
	fact[0]=1;
	p3[0]=1;
	FOR(i,1,N+1){
		fact[i]=fact[i-1]*i;
		p3[i]=p3[i-1]*3;
	}
	dp[1]=0;
	FOR(n,2,N+1){
		double a=0,b=0;
		FOR(i,1,n/2+1){
			REP(j,n-i+1){
				int k=n-i-j;
				if (j==0 || k==0 || (j>=i && k>i)){
					a+=C(n,i)*C(n-i,j)/p3[n-1]*dp[i];
				}
			}
		}
		b=1/p3[n-1];
		if (n%3==0){
			b+=C(n,n/3)*C(n*2/3,n/3)/p3[n];
		}
		dp[n]=(1+a)/(1-b);
	}
	printf("%.10f\n",dp[N]);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:18:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]

Judge Result