ac1189.pas

同济大学 Online在线题库 AC源代码合集 程序设计竞赛必看资料

program tju1189;
const
  maxn=500;
var
  adj:array[1..maxn,1..maxn]of boolean;
  route,dist,q:array[1..maxn]of word;
  m,n,i,j,f,r:word;
begin
  repeat
    fillchar(adj,sizeof(adj),0);
    fillchar(dist,sizeof(dist),255);
    read(m,n);
    for i:=1 to m do begin
      r:=0;
      repeat
        inc(r);read(route[r]);
        for j:=1 to r-1 do
          adj[route[j],route[r]]:=true;
      until seekeoln;
    end;

    f:=0;r:=1;q[1]:=1;dist[1]:=0;
    repeat
      inc(f);
      for i:=1 to n do
        if adj[q[f],i] and (dist[i]=65535) then begin
          inc(r);q[r]:=i;dist[i]:=dist[q[f]]+1;
        end;
    until (f=r) or (dist[n]<65535);
    if f=r then writeln('NO') else writeln(dist[n]-1);
  until seekeof;
end.