Vijos1734 NOI2010 海拔 平面图最小割

Posted 2020-07-28

建立平面图的对偶图，把最小割转化成最短路问题

Dijkstra算法堆优化

（被输入顺序搞WA了好几次T_T）

  1 #include <cstdio>
  2 #include <cstring>
  3 #include <algorithm>
  4 #include <queue>
  5 
  6 const int maxN=502;
  7 const int maxV=maxN*maxN;
  8 const int inf=0x3f3f3f3f;
  9 
 10 struct Edge
 11 {
 12     int to,next;
 13     int dist;
 14     void assign(int t,int n,int d)
 15         { to=t; next=n; dist=d; }
 16 };
 17 
 18 Edge elist[maxV*4];
 19 int head[maxV];
 20 int ecnt;
 21 int N;
 22 int dest;
 23 
 24 void initEdge()
 25 {
 26     memset(head,-1,sizeof(head));
 27     ecnt=0;
 28 }
 29 
 30 inline void addEdge(int from,int to,int dist)
 31 {
 32     elist[ecnt].assign(to,head[from],dist);
 33     head[from]=ecnt++;
 34 }
 35 
 36 void input()
 37 {
 38     scanf("%d",&N);
 39     dest=N*N+1;
 40     initEdge();
 41     int w;
 42     for(int j=0;j<=N;j++)
 43         for(int i=1;i<=N;i++)
 44         {
 45             scanf("%d",&w);
 46             if(!j) addEdge(0,i,w);
 47             else if(j==N) addEdge(N*N+i-N,dest,w);
 48             else addEdge(N*j+i-N,N*j+i,w);
 49         }
 50     for(int j=1;j<=N;j++)
 51         for(int i=0;i<=N;i++)
 52         {
 53             scanf("%d",&w);
 54             if(!i) addEdge(N*j+1-N,dest,w);
 55             else if(i==N) addEdge(0,N*j,w);
 56             else addEdge(N*j+i+1-N,N*j+i-N,w);
 57         }
 58     for(int j=0;j<=N;j++)
 59         for(int i=1;i<=N;i++)
 60         {
 61             scanf("%d",&w);
 62             if(!j || j==N) continue;
 63             else addEdge(N*j+i,N*j+i-N,w);
 64         }
 65     for(int j=1;j<=N;j++)
 66         for(int i=0;i<=N;i++)
 67         {
 68             scanf("%d",&w);
 69             if(!i || i==N) continue;
 70             else addEdge(N*j+i-N,N*j+i+1-N,w);
 71         }
 72 }
 73 
 74 struct Vertex
 75 {
 76     int idx;
 77     int dist;
 78     Vertex() {}
 79     Vertex(int i,int d):idx(i),dist(d) {}
 80     bool operator < (const Vertex& other) const
 81         { return this->dist > other.dist; }
 82 };
 83 
 84 int dist[maxV];
 85 int open[maxV];
 86 std::priority_queue<Vertex> que;
 87 
 88 int dijkstra()
 89 {
 90     memset(dist,0x3f,sizeof(dist));
 91     memset(open,1,sizeof(open));
 92     dist[0]=0; open[0]=false;
 93     int cur=0;
 94     while(cur!=dest)
 95     {
 96         for(int e=head[cur];e!=-1;e=elist[e].next)
 97         {
 98             int& to=elist[e].to;
 99             int& len=elist[e].dist;
100             if(open[to] && dist[to]>dist[cur]+len)
101             {
102                 dist[to]=dist[cur]+len;
103                 que.push(Vertex(to,dist[to]));
104             }
105         }
106         Vertex vt;
107         do { vt=que.top(); que.pop(); }
108         while(!open[vt.idx]);
109         cur=vt.idx;
110         open[cur]=false;
111     }
112     return dist[dest];
113 }
114 
115 int main()
116 {
117     input();
118     printf("%d\n",dijkstra());
119     return 0;
120 }