hdu4405 Aeroplane chess 期望

大牛说的很清楚。。点击打开链接

#include<iostream>#include<stdio.h>#include<string.h>using namespace std;double dp[100010];int flag[100010];int x,y;int main(){    int n,m;    while(scanf("%d%d",&n,&m)&&n!=0)    {        for(int i=0;i<=n;i++) dp[i]=0;        memset(flag,0,sizeof(flag));        while(m--)        {            scanf("%d%d",&x,&y);            flag[x]=y;        }        for(int i=n-1;i>=0;i--)        {            if(flag[i]) dp[i]=dp[flag[i]];            else            {                for(int j=1;j<=6;j++)                {                    if(i+j<=n)                    dp[i]+=(1.0/6)*dp[i+j];                    else break;                }                dp[i]+=1.0;            }        }        printf("%.4lf\n",dp[0]);    }}