1725 - Dice Probability.cpp

/*
Problem Name: Dice Probability
Problem Link: https://cses.fi/problemset/task/1725
Author: Sachin Srivastava (mrsac7)
*/
#include<bits/stdc++.h>
using namespace std;

template<typename... T>
#define error(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args); }
void err(istream_iterator<string> it) {}
template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {cerr << *it << "=" << a << ", "; err(++it, args...);}

#define int long long
#define pb push_back
#define F first
#define S second

const int inf = 1LL<<62;
const int md = 1000000007;

void solve(){
    int n,a,b; cin>>n>>a>>b;
    double dp[605][105]={0};
    dp[0][0] = 1.0;
    for (int j = 1; j<=n; j++) {
        for (int i = 1; i < 601; i++) {
            for (int k = 1; k < 7; k++) {
                if (i-k>=0) dp[i][j] += dp[i-k][j-1]*(1.0/6);
            }
        }
    }
    double ans =  0;
    for (int i = a; i <=b; i++) ans+= dp[i][n];
    cout<<setprecision(6)<<fixed;
    cout<<ans;
}    
signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    #ifdef LOCAL
    freopen("input.txt", "r" , stdin);
    freopen("output.txt", "w", stdout);
    #endif
    int t=1;
    //cin>>t;
    for (int i = 1; i <= t; i++) {
        solve();
        cout<<'\n';
    }
}