Алгоритмы на графах / structs / PQ

{ priority queue }
{ ®зҐаҐ¤м Ї® ЇаЁ®аЁвҐв ¬ ­  Ў §Ґ ¬­®Ј®Ї®§ЁжЁ®­­®Ј® ¤ҐаҐў }

const
maxn = 50;

type
key_type = integer;

tarray = array [1..maxn] of key_type;
parray = ^tarray;

type
priority_queue = object
{ private}
a: parray;
pq, qp: array [1..maxn] of integer;
d, n: integer;
procedure exch(i, j: integer);
procedure fixup(k: integer);
procedure fixdown(k, nn: integer);

public
constructor init(aa: parray; ad: integer);
function empty: boolean;
procedure insert(v: integer);
function getmin: integer;
procedure lower(k: integer);

end;

{ priority_queue }

procedure priority_queue.exch(i, j: integer);
var
t: integer;
begin
t := pq[i]; pq[i] := pq[j]; pq[j] := t;
qp[pq[i]] := i;
qp[pq[j]] := j;
end;

procedure priority_queue.fixup(k: integer);
begin
while (k > 1) and (a^[pq[(k+d-2) div d]] > a^[pq[k]]) do
begin
exch(k, (k+d-2) div d);
k := (k+d-2) div d;
end;
end;

procedure priority_queue.fixdown(k, nn: integer);
var
j, i: integer;
begin
j := d*(k-1)+2;

while j <= nn do
begin
i := j + 1;

while (i < j + d) and (i <= nn) do
begin
if (a^[pq[j]] > a^[pq[i]]) then
j := i;
inc(i);
end;
if a^[pq[k]] <= a^[pq[j]] then
break;
exch(k, j);
k := j;
j := d*(k-1)+2;
end;
end;

constructor priority_queue.init(aa: parray; ad: integer);
begin
d := ad;
a := aa;
end;

function priority_queue.empty: boolean;
begin
empty := n = 0;
end;

procedure priority_queue.insert(v: integer);
begin
inc(n);
pq[n] := v;
qp[v] := n;
fixup(n);
end;

function priority_queue.getmin: integer;
begin
exch(1, n);
fixdown(1, n-1);
getmin := pq[n];
dec(n);
end;

procedure priority_queue.lower(k: integer);
begin
fixup(qp[k]);
end;

var
pq: priority_queue;
aa: array [1..maxn] of integer;

procedure init;
var
i: integer;
begin
randomize;
writeln('prioryty queue');
for i := 1 to maxn do
aa[i] := random(1000);

pq.init(@aa, 2);

for i := 1 to maxn do
begin
pq.insert(i);
if random(5) = 0 then
begin
while not pq.empty do
begin
write(aa[pq.getmin], ' ');
end;
writeln;
end;
end;

{ aa[1] := 6;
aa[2] := 5;
aa[3] := 8;
aa[4] := 1;
aa[5] := 4;
aa[6] := 3;
aa[7] := 2;

pq.init(@aa, 2);

for i := 1 to 7 do
pq.insert(i);}
end;

procedure run;
begin
while not pq.empty do
write(aa[pq.getmin], ' ');
end;

begin
init;
run;
end.