Submission #6360849

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef vector<int> VI;
 
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
const int mod=1e9+7;

ll dp[2][210][105][105];

int a,b,c;

bool ddiv(ll d){
    while(d%2==0){
        d/=2;a++;
    }
    while(d%3==0){
        d/=3;b++;
    }
    while(d%5==0){
        d/=5;c++;
    }
    if(d!=1)return false;
    return true;
}

int main(){
    int n;cin>>n;
    ll d;cin>>d;
    if(!ddiv(d)){
        cout<<0<<endl;
        exit(0);
    }
    dp[0][0][0][0]=1;
    int cur=0;
    int next=1;
    ll ans=0;
    
    rep(i,n){
        rep(j,210) rep(k,105) rep(l,105) dp[next][j][k][l]=0;
        rep(j,205) rep(k,103) rep(l,103){
        dp[next][j][k][l]+=dp[cur][j][k][l];
        dp[next][j+1][k][l]+=dp[cur][j][k][l];
        dp[next][j][k+1][l]+=dp[cur][j][k][l];
        dp[next][j+2][k][l]+=dp[cur][j][k][l];
        dp[next][j][k][l+1]+=dp[cur][j][k][l];
        dp[next][j+1][k+1][l]+=dp[cur][j][k][l];
        }

        swap(cur,next);
        
    }
    rep(i,a,210) rep(j,b,105) rep(k,c,105){
        ans+=dp[cur][i][j][k];
    }
    double res=ans/pow(6,n);
    cout<<fixed<<setprecision(14)<<res<<endl;
}

Submission Info

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