记录编号	21523	评测结果	AAWAAAAATT
题目名称	奶牛派对	最终得分	70
用户昵称	make	是否通过	未通过
代码语言	Pascal	运行时间	3.075 s
提交时间	2010-11-11 09:57:58	内存使用	3.93 MiB

program party;
var
 h:array [1..1000,1..1000] of longint;
 n,m,x,max:longint;
 f1,f2:text;

procedure init;
var i,j,k,u:longint;
begin
 assign(f1,'party.in'); reset(f1);
 assign(f2,'party.out'); rewrite(f2);
 readln(f1,n,m,x);
 for i:=1 to n do
  for j:=1 to n do
   h[i,j]:=maxlongint;
 for u:=1 to m do begin
  readln(f1,i,j,k);
  if h[i,j]<>maxlongint then begin if k<h[i,j] then h[i,j]:=k; end
  else h[i,j]:=k;
 end;
 close(f1);
 max:=-1;
end;

procedure play;
var
 i,j,k:longint;
begin
 for k:=1 to n do
  for i:=1 to n do
   for j:=1 to n do
    if (h[i,k]<>maxlongint)and(h[k,j]<>maxlongint) then
     if (h[i,k]+h[k,j]<h[i,j]) then
      h[i,j]:=h[i,k]+h[k,j];
end;


procedure search;
var i,j:longint;
begin
 for i:=1 to n do
  if h[i,x]+h[x,i]>max then max:=h[i,x]+h[x,i];
 writeln(f2,max);
 close(f2);
end;

begin
 init;
 play;
 search;
end.