BZOJ1001 狼抓兔子 终于过了！

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<queue>
  4 #include<cstring>
  5 #define maxn 2100009
  6 #define rep(i,j,k) for(int i = j; i <= k; i++)
  7 using namespace std;
  8 
  9 int read()
 10 {
 11     int s = 0, t = 1; char c = getchar();
 12     while( !isdigit(c) ) {
 13         if( c == ‘-‘ ) t = -1; c = getchar();
 14     }
 15     while( isdigit(c) ){
 16         s = s * 10 + c - ‘0‘; c = getchar();
 17     } 
 18     return s * t;
 19 }
 20 
 21 int d[maxn], n, m, sx, tx;
 22 bool done[maxn] = {0}; 
 23 
 24 struct node{
 25 int d, u;
 26 bool operator < (const node& rhs) const{
 27         return d > rhs.d;
 28      }
 29 };
 30 
 31 struct edge{
 32 int to, key;
 33 edge* next;
 34 };
 35 
 36 edge *pt, edges[maxn*3], *head[maxn];
 37 
 38 void add_edge(int x,int y,int val){
 39    pt->to = y;pt->key = val;
 40    pt->next = head[x];
 41    head[x] = pt++;
 42    pt->to = x, pt->key= val;
 43    pt->next = head[y];
 44    head[y] = pt++; 
 45 }
 46 priority_queue<node> Q;
 47 
 48 void dijkstra()
 49 {
 50      memset(d,127,sizeof(d));
 51      d[sx] = 0;
 52      Q.push((node){0,sx});
 53      while( !Q.empty() ){
 54         node x = Q.top(); Q.pop();
 55         int u = x.u;
 56         if( done[u] ) continue;
 57         done[u] = 1;
 58         for( edge*i = head[u]; i ; i = i->next ){
 59             int y = i->to, key = i->key;
 60             if( d[y] > d[u]+key ) {
 61                 d[y] = d[u]+key;
 62                 Q.push((node){d[y],y});
 63             }
 64         }
 65      }
 66 }
 67 
 68 int main()
 69 {
 70     //freopen("out.txt","w",stdout);
 71    pt = edges;
 72    n = read(), m = read(); 
 73    sx = 0, tx = (n-1)*(m-1) * 2+ 1;
 74    rep(i,0,n-1) {
 75       int xx = (2*m-2)*i;
 76       int xy = (2*m-2)*(i-1);
 77       rep(j,1,m-1){
 78          int x = read();
 79          if( !i ) {
 80             add_edge(xx+2*j,tx,x);
 81             //cout<<tx<<" "<<xx+2*j+1<<" "<<x<<endl;
 82          } 
 83          else if( i == n-1 ) {
 84             add_edge(sx,xy+2*j-1,x);
 85             //cout<<xy+2*j<<" "<<sx<<" "<<x<<endl;
 86          }
 87          else{
 88             add_edge(xx+2*j,xy+2*j-1,x);
 89             //cout<<xy+2*j<<" "<<xx+2*j+1<<" "<<x<<endl;
 90          }
 91       }
 92    }
 93    rep(i,0,n-2){
 94       int xx = 2*(m-1)*(i);
 95       rep(j,1,m){
 96          int x = read();
 97          if( j == 1 ){
 98             add_edge(sx,xx+2*j-1,x);
 99             //cout<<sx<<" "<<xx<<" "<<x<<endl;
100          } 
101          else if( j == m ){
102             add_edge(tx,xx+2*j-2,x);
103             //cout<<tx<<" "<<xx+2*j-1<<" "<<x<<endl;
104          }
105          else {
106             add_edge(xx+2*j-2,xx+2*j-1,x);
107             //cout<<xx+2*j<<" "<<xx+2*j-1<<" "<<x<<endl;
108          }
109       }
110    }
111    rep(i,0,n-2){
112      int xx = 2*(m-1)*(i); 
113      rep(j,1,m-1){
114         int x = read();
115         add_edge(xx+2*j,xx+2*j-1,x);
116         //cout<<xx+2*j<<" "<<xx+2*j+1<<" "<<endl;
117      }
118    }
119    dijkstra();
120    cout<<d[tx]<<endl;
121    return 0;
122 }