[BZOJ 1001 狼抓兔子]

標籤：

平面圖的對偶圖轉化，具體請看周冬大神的論文

建邊時需稍微注意

下面是代碼：

 1 #include<cstdio> 2 #include<cstdlib> 3 #include<cstring> 4 #include<iostream> 5 #include<algorithm> 6 #define N 1010 7 #define inf 0x7fffffff 8 using namespace std; 9 10 const int maxn=N*N*2,maxm=maxn*3;11 int n,m,s,t,p,d,p1,p2;12 int head[maxn],go[maxm],next[maxm],w[maxm];13 14 void build(int a,int b,int c)15 {16     go[++p]=b;17     next[p]=head[a];18     w[p]=c;19     head[a]=p;20 }21 22 void Double_build(int a,int b,int c)23 {24     build(a,b,c);25     build(b,a,c);26 }27 28 int num(int a,int b){return (((a-1)*(m-1)+b)*2);}29 30 int que[maxn],lead,tail,use[maxn],dis[maxn],node;31 32 void spfa()33 {34     memset(use,0,sizeof use);35     for (int i=s;i<=t;i++) dis[i]=inf;36     lead=tail=1;que[1]=s;use[s]=1;dis[s]=0;37     for (;lead<=tail;lead++,use[node]=0)38     {39         node=que[lead%maxn];40         for (int i=head[node];i;i=next[i]) if (dis[go[i]]>dis[node]+w[i])41         {42             dis[go[i]]=dis[node]+w[i];43             if (!use[go[i]])44             {45                 use[go[i]]=1;46                 que[(++tail)%maxn]=go[i];47             }48         }49     }50 }51 52 int main()53 {54     scanf("%d%d",&n,&m);55     s=1;t=(n-1)*m*2;56     for (int i=1;i<=n;i++)57         for (int j=1;j<m;j++)58         {59             scanf("%d",&d);60             p1=i==1?t:num(i-1,j)+1;p2=i==n?s:num(i,j);61             Double_build(p1,p2,d);62         }63     for (int i=1;i<n;i++)64         for (int j=1;j<=m;j++)65         {66             scanf("%d",&d);67             p1=j==1?s:num(i,j-1);p2=j==m?t:num(i,j)+1;68             Double_build(p1,p2,d);69         }70     for (int i=1;i<n;i++)71         for (int j=1;j<m;j++)72         {73             scanf("%d",&d);74             p1=num(i,j);p2=p1+1;75             Double_build(p1,p2,d);76         }77     spfa();78     printf("%d",dis[t]);79     return 0;80 }

 

[BZOJ 1001 狼抓兔子]