工厂的烦恼

题意：

找出一条最长路

思路：

最短路的符号改成大于号就好了….

const
 maxn=100;
 manv=1000;
var
 a:array [0..maxn,0..maxn] of longint;
 x,y,i,j,n,m,k,z,max,s:longint;
begin
 readln(n,m);
 fillchar(a,sizeof(a),250);
 for i:=1 to m do
 begin
  readln(x,y,z);
  a[x,y]:=z;
 end;
  for k:=1 to n do
   for i:=1 to n do
    for j:=1 to n do
     if (k<>i) and (i<>j) and (j<>k) then
      if (a[i,j]<a[i,k]+a[k,j]) and (a[i,k]>-5201314) and (a[k,j]>-5201314) then
       a[i,j]:=a[i,k]+a[k,j];
 max:=-maxlongint;
 for i:=1 to n do
  for j:=1 to n do
   if a[i,j]>max then max:=a[i,j];
 writeln(max);
end.