poj3463

【题意】

给定一个有向加权图，求s到f的最短路径和比最短路径长1的路径数

【输入】

多组数据，第一行一个数字t表示有多少组数据

每组数据第一行两个数n、m表示点的个数和边的个数(n<=1000,m<=10000)

接下来m行每行三个整数a、b、l表示存在一条长度为l连接a、b的有向边

最后一行两个整数s、f

【输出】

对于每组数据输出一行，该行一个整数表示路径数

heap+dijkstra

如果用A*的话会超时，因为最终答案是10^8等级的

每个点维护两个值，最小值和次小值，再加上计数即可，代码略显臃肿

program poj3463;var  ans,tot,n,m,i,j,k,t,s,f,a,b,l:longint;  root:array [0..10001] of longint;  rank,count,dis:array [0..1,0..10001] of longint;  next,point,cost:array [0..100001] of longint;  heap,mode:array [0..20001] of longint;procedure swap (var a,b:longint);var  i:longint;begin  i:=a;  a:=b;  b:=i;end;procedure connect (a,b,l:longint);begin  inc(tot);  point[tot]:=b;  cost[tot]:=l;  next[tot]:=root[a];  root[a]:=tot;end;procedure insert (o,now:longint);var  i:longint;begin  inc(tot);  heap[tot]:=now;  mode[tot]:=o;  rank[o,now]:=tot;  i:=tot;  while (i>1)and(dis[mode[i div 2],heap[i div 2]]>dis[o,now]) do    begin      swap(rank[mode[i div 2],heap[i div 2]],rank[o,now]);      swap(mode[i div 2],mode[i]);      swap(heap[i div 2],heap[i]);      i:=i div 2;    end;end;procedure delete (o,now:longint);var  i:longint;begin  if rank[o,now]=0 then exit;  if rank[o,now]=tot then    begin      heap[tot]:=0;      mode[tot]:=0;      rank[o,now]:=0;      dec(tot);      exit;    end;  i:=rank[o,now];  swap(rank[o,now],rank[mode[tot],heap[tot]]);  swap(heap[i],heap[tot]);  swap(mode[i],mode[tot]);  rank[o,now]:=0;  heap[tot]:=0;  mode[tot]:=0;  dec(tot);  if (i>1)and(dis[mode[i div 2],heap[i div 2]]>dis[mode[i],heap[i]]) then    while (i>1)and(dis[mode[i div 2],heap[i div 2]]>dis[mode[i],heap[i]]) do      begin        swap(rank[mode[i div 2],heap[i div 2]],rank[mode[i],heap[i]]);        swap(mode[i],mode[i div 2]);        swap(heap[i],heap[i div 2]);        i:=i div 2;      end                                                                     else    while (dis[mode[i*2],heap[i*2]]<dis[mode[i],heap[i]])or    (dis[mode[i*2+1],heap[i*2+1]]<dis[mode[i],heap[i]]) do      if dis[mode[i*2],heap[i*2]]<dis[mode[i*2+1],heap[i*2+1]] then        begin          swap(rank[mode[i * 2],heap[i * 2]],rank[mode[i],heap[i]]);          swap(mode[i],mode[i * 2]);          swap(heap[i],heap[i * 2]);          i:=i * 2;        end                                                               else        begin          swap(rank[mode[i * 2 + 1],heap[i * 2 + 1]],rank[mode[i],heap[i]]);          swap(mode[i],mode[i * 2 + 1]);          swap(heap[i],heap[i * 2 + 1]);          i:=i * 2 + 1;        endend;procedure spfa;var  who,now,i,j,k:longint;begin  while tot>0 do    begin      who:=heap[1];      now:=mode[1];      delete(now,who);      k:=root[who];      while k<>0 do        begin          if dis[now,who]+cost[k]<dis[0,point[k]] then            begin              swap(dis[0,point[k]],dis[1,point[k]]);              count[1,point[k]]:=count[0,point[k]];              dis[0,point[k]]:=dis[now,who]+cost[k];              count[0,point[k]]:=count[now,who];              delete(0,point[k]);              delete(1,point[k]);              insert(0,point[k]);              insert(1,point[k]);            end                                                  else          if dis[now,who]+cost[k]=dis[0,point[k]] then            count[0,point[k]]:=count[0,point[k]]+count[now,who]                                                  else          if dis[now,who]+cost[k]<dis[1,point[k]] then            begin              dis[1,point[k]]:=dis[now,who]+cost[k];              count[1,point[k]]:=count[now,who];              delete(1,point[k]);              insert(1,point[k]);            end                                                  else          if dis[now,who]+cost[k]=dis[1,point[k]] then            count[1,point[k]]:=count[1,point[k]]+count[now,who];          k:=next[k];        end;    end;end;begin  read(t);  while t>0 do    begin      fillchar(root,sizeof(root),0);      fillchar(heap,sizeof(heap),0);      fillchar(mode,sizeof(mode),0);      fillchar(dis,sizeof(dis),63);      fillchar(count,sizeof(count),0);      tot:=0;      read(n,m);      for i:=1 to m do        begin          read(a,b,l);          connect(a,b,l);        end;      read(s,f);      tot:=0;      dis[0,s]:=0;      count[0,s]:=1;      insert(0,s);      spfa;      ans:=count[0,f];      if dis[0,f]+1=dis[1,f] then ans:=ans+count[1,f];      writeln(ans);      dec(t);    end;end.