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Файл:Алгоритмы на графах / shortest / dijkslst
.pas{ graphs by boris }
{ shortest path from one to all (Dijkstra's algorithm) }
{ adjacency lists}
const
maxn = 100000;
inf = maxint div 2;
type
pnode = ^tnode;
tnode = record
v: word;
weight: integer;
next: pnode;
end;
var
a: array [1..maxn] of pnode;
d: array [1..maxn] of longint;
p: array [1..maxn] of integer;
visited: array [1..maxn] of boolean;
s, n: longint;
procedure insert_vertex(v, w: word; weight: integer);
var
p: pnode;
begin
new(p);
p^.v := w;
p^.weight := weight;
p^.next := a[v];
a[v] := p;
end;
procedure init;
var
i, j, x, y, nn, z: longint;
begin
for i := 1 to maxn do
begin
a[i] := nil;
d[i] := inf;
end;
fillchar(p, sizeof(p), 0);
fillchar(visited, sizeof(visited), false);
{ assign(input, 'dijkstra.in');}
assign(input, 'randw.in');
reset(input);
read(n);
read(nn);
for i := 1 to nn do
begin
read(x, y, z);
insert_vertex(x, y, z);
{ a[y, x] := z;} { Ґб«Ё Ґ®аЁҐвЁа®ў л© Ја д }
end;
end;
procedure print;
var
i: longint;
p: pnode;
begin
writeln;
writeln('number of vertex : ', n);
writeln('adjacency lists');
for i := 1 to n do
begin
p := a[i];
write('[', i, '] ');
while p <> nil do
begin
write(p^.v, ' (', p^.weight, ') ');
p := p^.next;
end;
writeln;
end;
end;
procedure dijkstra(s: integer);
var
j, i, min, v, weight: integer;
t: pnode;
begin
t := a[s];
while t <> nil do
begin
d[t^.v] := t^.weight;
t := t^.next;
end;
for v := 1 to n do
p[v] := s;
d[s] := 0;
p[s] := 0;
visited[s] := true;
for j := 2 to n do
begin
min := inf;
for i := 1 to n do
if (not visited[i]) and (d[i] < min) then
begin
min := d[i];
v := i;
end;
t := a[v];
visited[v] := true;
while t <> nil do
begin
if d[t^.v] > d[v] + t^.weight then
begin
d[t^.v] := d[v] + t^.weight;
p[t^.v] := v;
end;
t := t^.next;
end;
end;
end;
procedure print_path(x: integer);
begin
if x <> s then
print_path(p[x]);
write(x, ' ');
end;
var
i: longint;
begin
init;
writeln('shortest path from one to all (Dijkstra''s algorithm)');
s := 1;
dijkstra(s);
{ for i := 1 to n do
if d[i] <> inf then
write(i, '-', d[i], ' ');
print;}
end.