PKU1172 street race

       这道题目考察搜索的一个基本应用——计算连同子图。我们采取的是试删法，一次每句每个顶点判断是否符合题意即可。

program street_race;const maxn=100;type pointer=^node; node=record data:longint; next:pointer; end;var edge:array[0..maxn] of pointer; ansa,ansb:array[0..maxn] of longint; g:array[0..maxn,0..maxn] of boolean; vis:array[0..maxn] of boolean; n,lena,lenb:longint;procedure prework;var i:longint;begin for i:=0 to maxn do edge[i]:=nil; fillchar(g,sizeof(g),0); n:=0; lena:=0; lenb:=0;end;procedure init;var k:longint; p:pointer;begin read(k); while k<>-1 do begin while k<>-2 do begin g[n,k]:=true; new(p); p^.data:=k; p^.next:=edge[n]; edge[n]:=p; read(k); end; read(k); inc(n); end;end;procedure dfs(x:longint);var p:pointer;begin vis[x]:=true; p:=edge[x]; while p<>nil do begin if not vis[p^.data] then dfs(p^.data); p:=p^.next; end;end;procedure main;var i,j,k:longint; flag:boolean;begin for i:=1 to n-1 do begin fillchar(vis,sizeof(vis),0); vis[i]:=true; dfs(0); if not vis[n] then begin inc(lena); ansa[lena]:=i; flag:=true; vis[i]:=false; for j:=0 to n do for k:=0 to n do if not vis[j] and vis[k] and g[j,k] then begin flag:=false; break; end; if flag then begin inc(lenb); ansb[lenb]:=i; end; end; end;end;procedure outit;var i:longint;begin write(lena); for i:=1 to lena do write(' ',ansa[i]); writeln; write(lenb); for i:=1 to lenb do write(' ',ansb[i]); writeln;end;begin assign(input,'a.in'); reset(input); assign(output,'a.out'); rewrite(output); prework; init; main; outit; close(input); close(output);end.