bzoj1744 [Usaco2005 oct]Skiing 奶牛滑雪

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fd(i,a,b) for(int i=a;i>=b;i--)
#define inf 1000000000
using namespace std;
const int N=1e5+5;
int a
;
const int M=1e3+5;
typedef double db;
const db eps=1e-6;
int mp[M][M];
bool vis[M][M];
struct node
{
int x,y;
}q
;
int ans,v;
const int dx[4]={0,1,0,-1};
const int dy[4]={1,0,-1,0};
int n,m;
db speed
,dis[M][M];
bool inr(int x,int y)
{
if (x<=n&&x>=1&&y<=m&&y>=1)return 1;
return 0;
}
unsigned int t,w;
inline void add(int x,int y,double z)
{
if (z<dis[x][y])
{
dis[x][y]=z;
if (vis[x][y])return;
vis[x][y]=1,q[++w].x=x,q[w].y=y;
}
}

int main()
{
scanf("%d%d%d",&v,&n,&m);
fo(i,1,n)
{
fo(j,1,m)scanf("%d",&mp[i][j]);
}
speed[100]=1;
fo(i,1,100)speed[i+100]=speed[i+99]*2;
fd(i,99,1)speed[i]=speed[i+1]/2;
fo(i,1,n)
fo(j,1,m)dis[i][j]=1e10;
add(1,1,0);
t=1;
while (t!=w+1)
{
int x=q[t].x,y=q[t++].y;
fo(k,0,3)
{
int x1=x+dx[k];
int y1=y+dy[k];
if (inr(x1,y1))
{
add(x1,y1,dis[x][y]+speed[mp[x][y]-mp[1][1]+100]);
}
}
vis[x][y]=0;
}
/*fo(i,1,n)
{
fo(j,1,m)printf("%.2lf(%.2lf) ",dis[i][j],speed[i][j]);
printf("\n");
}*/
printf("%.2f",1.0*dis
[m]/v);
}