POJ 1523（求割点）

求割点入门题！

……死调一下午+晚上才发现把‘node'打成’nodes'了……

Program P1523;const   maxedge=999000;   maxn=10000;var   edge,tail:array[1..maxedge] of longint;   size:longint;   head:array[1..maxn] of longint;   n,i,j,ans,k:longint;   b,cut:array[1..maxn] of boolean;   time,root:longint;   a,d,ancestor,c:array[1..maxn] of longint;procedure addedge(u,v:longint);begin   inc(size);   edge[size]:=v;   tail[size]:=head[u];   head[u]:=size;end;function min(a,b:longint):longint;begin   if a<b then exit(a) else exit(b);end;function max(a,b:longint):longint;begin   if a>b then exit(a) else exit(b);end;procedure Dfs(k,father,deep:longint);var   i,j,p,tot:longint;begin   tot:=0;   c[k]:=1;   d[k]:=deep;   ancestor[k]:=deep;   p:=head[k];   while (p>0) do   begin      i:=edge[p];      if (i<>father) and (c[i]=1) then ancestor[k]:=min(ancestor[k],d[i]);      if (c[i]=0) then      begin         dfs(i,k,deep+1);         inc(tot);         ancestor[k]:=min(ancestor[k],ancestor[i]);         if (k=root) and (tot>=2) then cut[k]:=true;         if (k<>root) and (ancestor[i]>=d[k]) then cut[k]:=true;      end;      p:=tail[p];   end;   c[k]:=2;   inc(time);   a[k]:=time;end;procedure Dfs2(k:longint);var   i,p:longint;begin   b[k]:=true;   p:=head[k];   while (p>0) do   begin      i:=edge[p];      if not(b[i]) then      begin         dfs2(i);      end;      p:=tail[p];   end;end;function main:boolean;var   i,j,p,ans:longint;begin   time:=0;   main:=false;   for i:=1 to maxn do      if (head[i]>0) and (c[i]=0) then      begin        root:=i;        dfs(root,0,1);      end;   for i:=1 to maxn do      if cut[i] then      begin         main:=true;         ans:=0;         fillchar(b,sizeof(b),false);         b[i]:=true;         p:=head[i];         while (p>0) do         begin            if not(b[edge[p]]) then            begin               dfs2(edge[p]);               inc(ans);            end;            p:=tail[p];         end;         writeln('  SPF node ',i,' leaves ',ans,' subnets');      end;end;begin {  assign(input,'p1523.in');   reset(input);    }   k:=1;   while not seekeof do   begin      size:=0;      fillchar(head,sizeof(head),0);      fillchar(edge,sizeof(edge),0);      fillchar(tail,sizeof(tail),0);      fillchar(cut,sizeof(cut),false);      fillchar(c,sizeof(c),0);      fillchar(d,sizeof(d),0);      fillchar(ancestor,sizeof(ancestor),0);      read(i);      if i=0 then break;      read(j);      while (i>0) do      begin         addedge(i,j);         addedge(j,i);         read(i);         if i=0 then break;         read(j);      end;      ans:=0;      writeln('Network #',k);      if not(main) then writeln('  No SPF nodes');      writeln;      inc(k);   end;end.