解题：BJOI 2006 狼抓兔子

 1 #include<queue>
 2 #include<cstdio>
 3 #include<cctype> 
 4 #include<cstring>
 5 #include<algorithm>
 6 using namespace std;
 7 const int N=2000005,M=6000005;
 8 struct a{int node,dist;};
 9 bool operator < (a x,a y)
10 {
11     return x.dist>y.dist;
12 }
13 priority_queue<a> hp;
14 int p[N],noww[2*M],goal[2*M],val[2*M],dis[N],vis[N];
15 int n,m,rd,st,ed,bs,t1,t2,cnt;
16 void Read(int &x)
17 {
18     x=0; char ch=getchar();
19     while(!isdigit(ch))
20         ch=getchar();
21     while(isdigit(ch))
22         x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
23 }
24 void Link(int f,int t,int v) 
25 {
26     noww[++cnt]=p[f],p[f]=cnt;
27     goal[cnt]=t,val[cnt]=v;
28 }
29 int ID(int a,int b,int c)
30 {
31     if(a>n||!b) return st;
32     if(!a||b>m) return ed;
33     return (a-1)*m+b+c*n*m;
34 }
35 void Dijkstra()
36 {
37     memset(dis,0x3f,sizeof dis);
38     dis[st]=0,hp.push((a){st,0});
39     while(!hp.empty())
40     {
41         a tt=hp.top(); hp.pop(); int tn=tt.node;
42         if(vis[tn]) continue; vis[tn]=true;
43         for(int i=p[tn];i;i=noww[i])
44             if(dis[goal[i]]>dis[tn]+val[i])
45             {
46                 dis[goal[i]]=dis[tn]+val[i];
47                 hp.push((a){goal[i],dis[goal[i]]});
48             }
49     }
50 }
51 int main()
52 {
53     register int i,j;
54     Read(n),Read(m);
55     n--,m--,st=2*n*m+1,ed=st+1;
56     for(i=1;i<=n+1;i++)
57         for(j=1;j<=m;j++)
58         {
59             Read(rd),t1=ID(i,j,1),t2=ID(i-1,j,0);
60             Link(t1,t2,rd),Link(t2,t1,rd);
61         }
62     for(i=1;i<=n;i++)
63         for(j=1;j<=m+1;j++)
64         {
65             Read(rd),t1=ID(i,j,0),t2=ID(i,j-1,1);
66             Link(t1,t2,rd),Link(t2,t1,rd);
67         }
68     for(i=1;i<=n;i++)
69         for(j=1;j<=m;j++)
70         {
71             Read(rd),t1=ID(i,j,0),t2=ID(i,j,1);
72             Link(t1,t2,rd),Link(t2,t1,rd);
73         }
74     Dijkstra(); printf("%d",dis[ed]);
75     return 0;
76 }