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## Discussion of Problem 1450. Russian Pipelines

WA6
Posted by Kirin Vladislav 26 Feb 2007 11:59
WA6. What's wrong? Give some test's. In my solution I used Deixtra algo.
Re: WA6
Posted by Anton [SUrSU] 26 Feb 2007 14:25
Why Dijkstra?
Simple dfs for topsort and then dp.
Re: WA6
Posted by @ntiFreeze 27 Feb 2007 00:57
I think this problem could not be solved with dijkstra.
Simple dfs for topsort and then dp or simple BFS :)
Re: WA6
Posted by Rustam 16 Apr 2008 21:36
i used FLOYD's algo and have TLE15. i used Djkstra's algo and i have WA10.. pls, can you give me some tests or what's bug in my program?

{\$APPTYPE CONSOLE}

uses
SysUtils;

var a:array [1..1000,1..1000] of longint;
mas:array [1..1000] of longint;
used:array [1..1000] of boolean;
i,n,m,t,f:longint;
procedure djkstra(st:longint);
var cur,i:longint;
begin
fillchar(mas,sizeof(mas),255);
fillchar(used,sizeof(used),0);
cur:=st;
mas[cur]:=0;
repeat
used[cur]:=true;
for i:=1 to n do
if (a[cur,i]<>0) and (mas[i]<mas[cur]+a[cur,i]) then
mas[i]:=mas[cur]+a[cur,i];
cur:=0;
for i:=1 to n do
if not used[i] and (mas[i]<>-1)and ((cur=0)or (mas[cur]>mas[i])) then cur:=i;
until cur=0;
end;
begin
for i:=1 to m do
begin
end;
djkstra(t);
if mas[f]<>-1 then write(mas[f]) else write('No solution');
halt(0);
end.

and what to do if there is cycle?
Edited by author 16.04.2008 21:52

Edited by author 16.04.2008 21:56
Re: WA6
Posted by awpris 16 Apr 2008 22:52

Edited by author 16.04.2008 22:55
Re: WA6
Posted by Rustam 8 Jul 2008 00:32
i've changed djkstra like this
<code>procedure djkstra(x:longint);
var cur,i:longint;
begin
fillchar(v,sizeof(v),-1);
fillchar(used,sizeof(used),0);
v[x]:=0;
cur:=x;
repeat
used[cur]:=true;
for i:=1 to n do
if (a[cur,i]<>0) and ((v[i]=-1)or (v[i]<v[cur]+a[cur,i])) then
begin
v[i]:=v[cur]+a[cur,i];
used[i]:=false;
end;
cur:=0;
for i:=1 to n do
if not used[i] and (v[i]<>-1)and((cur=0)or (v[cur]<v[i])) then
cur:=i;
until cur =0;
end;</code>
and it's tle#15(((