bzoj 1001 狼抓兔子

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <queue>
 5 const int N = 1000 + 7, M = 2000000 + 7, inf = 1 << 30;
 6 using namespace std;
 7 int n,m,s,t,cnt,head[M],dis[M];
 8 bool used[M];
 9 struct edges
10 {
11     int nxt,to,wi;
12 } E[M * 3];
13  
14 int idid(int a,int b)
15 {
16     return (a - 1) * (m - 1) * 2 + b * 2;
17 }
18  
19 void add(int u,int v,int wi)
20 {
21     E[++cnt] = (edges){head[u],v,wi};head[u] = cnt;
22     E[++cnt] = (edges) {head[v],u,wi}; head[v] = cnt;
23 }
24  
25 void Init()
26 {
27     scanf("%d%d",&n,&m);
28     if(n == 1 || m == 1)
29     {
30         if(n == 1) swap(n,m); 
31         int ans =  inf, c;
32         for(int i = 1; i < n; ++i)
33         {
34             scanf("%d",&c);
35             ans = min(ans,c);
36         }
37         printf("%d\n",ans); return;
38     }
39     int c;s = 0, t = ((n-1) * (m-1) << 1) + 1;
40     for(int i = 1; i <= n; ++i)
41     for(int j = 1; j < m; ++j)
42     {
43         scanf("%d",&c); 
44         if(i == 1) add(s,j<<1,c);
45         else if(i == n) add(idid(i-1,j)-1,t,c);
46         else add(idid(i-1,j)-1,idid(i,j),c);
47     }
48  
49     for(int i = 1; i < n; ++i)
50     for(int j = 1; j <= m; ++j)
51     {
52         scanf("%d",&c);
53         if(j == 1) add(idid(i,j)-1,t,c);
54         else if(j == m) add(s,idid(i,j-1),c);
55         else add(idid(i,j-1),idid(i,j)-1,c);
56     }
57     for(int i = 1;i < n; ++i)
58     for(int j = 1 ; j < m; ++j)
59     {
60         scanf("%d",&c);
61         add(idid(i,j)-1,idid(i,j),c);
62     }
63 }
64  
65 void dij()
66 {
67     queue<int> Q;
68     memset(dis,127/2,sizeof(dis));
69     memset(used,false,sizeof(used)); used[s] = true;
70     Q.push(s); dis[s] = 0;
71     while(!Q.empty())
72     {
73         int u = Q.front(); Q.pop(); used[u] = false;
74         for(int i = head[u]; i; i = E[i].nxt)
75         {
76             int v = E[i].to;
77             if(dis[v] <= dis[u] + E[i].wi) continue;
78             dis[v] = dis[u] + E[i].wi;
79             if(used[v]) continue;
80             Q.push(v); used[v] = true;
81         }
82     }
83 }
84  
85 void Solve()
86 {
87     dij();
88     printf("%d\n",dis[t]);
89 }
90  
91 int main()
92 {
93 //  freopen("1.in","r",stdin);
94     Init();
95     if(n == 1 || m == 1) return 0;
96     Solve();
97     return 0;
98 }
99