Aeroplane chess HDU-4405 期望DP

Aeroplane chess

code

/*Siberian Squirrel*/
/*Cute KiloFish*/
#include<bits/stdc++.h>

#define IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define ACM_LOCAL

using namespace std;
typedef long long ll;

const double PI = acos(-1);
const double eps = 1e-4;
/*const int MOD = 998244353, r = 119, k = 23, g = 3;
const int MOD = 1004535809, r = 479, k = 21, g = 3;*/
const int MOD = 1e9 + 7;
const int M = 1e3 + 10;
const int N = 1e6 + 10;

//inline int rnd(){static int seed=2333;return seed=(((seed*666666ll+20050818)%998244353)^1000000007)%1004535809;}

int n, m;
int x, y;
double dp[N];
int fly[N];

void solve() {
    
    
    for(int i = 1; i <= m; ++ i) {
    
    
        cin >> x >> y;
        fly[x] = y;
    }
    for(int i = n; i >= 0; -- i) {
    
    
        dp[i] = 0;
        for(int j = 1; j <= 6; ++ j) {
    
    
            if(i + j >= n) {
    
    
                dp[i] += dp[n] / 6.0;
            } else {
    
    
                dp[i] += dp[i + j] / 6.0;
            }
        }
        dp[i] ++;
        if(fly[i] != -1) dp[i] = dp[fly[i]];
    }
    cout << fixed << setprecision(4) << dp[0] - 1 << endl;

}

int main() {
    
    
    IO;
#ifdef ACM_LOCAL
    freopen("input", "r", stdin);
    freopen("output", "w", stdout);
#endif
    int o = 1, cases = 0;
//    cin >> o;
    while(o --) {
    
    
        while(cin >> n >> m) {
    
    
            memset(fly, -1, sizeof(int) * (n + 1));
            if(n + m) solve();
            else break;
        }
    }
    return 0;
}