Aeroplane chess hdu 4405

Aeroplane chess
Time Limit: 1000msMemory Limit: 32768KB This problem will be judged on HDU. Original ID: 4405
64-bit integer IO format: %I64d Java class name: Main
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Hzz loves aeroplane chess very much. The chess map contains N+1 grids labeled from 0 to N. Hzz starts at grid 0. For each step he throws a dice(a ice have six faces with equal probability to face up and the numbers on the faces are 1,2,3,4,5,6). When Hzz is at grid i and the dice number is x, he will moves to grid i+x. Hzz finishes the game when i+x is equal to or greater than N.

There are also M flight lines on the chess map. The i-th flight line can help Hzz fly from grid Xi to Yi (0

#include<stdio.h>#include<string.h>double dp[100010];int vis[100010];int main(){    int n, m;    while (~scanf("%d %d",&n,&m)&&(n+m))    {        memset(vis, -1, sizeof(vis));        int a, b;        while (m--)        {            scanf("%d %d", &a, &b);            vis[a] = b;        }        int i, j;        memset(dp, 0, sizeof(dp));        for (i = n - 1; i >= 0; i--)        {            if (vis[i] == -1)            {                for (j = 1; j < 7; j++)                {                    dp[i] += dp[i + j] / 6.0;                }                dp[i] += 1;            }            else                dp[i] = dp[vis[i]];        }        printf("%.4lf\n", dp[0]);    }    return 0;}