hdu 4405 Aeroplane chess (期望dp入门)

http://acm.hdu.edu.cn/showproblem.php?pid=4405

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
using namespace std;

const int mx=100000+10;
int v[mx];
double dp[mx];

int main()
{
    int n,m,x,y,i,j;
    while (cin>>n>>m)
    {
        memset(v,0,sizeof(v));
        memset(dp,0,sizeof(dp));
        if (!n&&!m) return 0;
        while (m--)
        {
            cin>>x>>y;
            v[x]=y;
        }
        for (i=n-1;i>=0;i--)
        {
            if (v[i]) {dp[i]=dp[v[i]];continue;}
            for (j=i+1;j<=i+6;j++)
                dp[i]+=(dp[j]+1)/6.0;
        }
        printf("%.4lf
",dp[0]);
    }
}