RosettaCodeData/Task/Partition-function-P/PascalABC.NET/partition-function-p.pas

49 lines
887 B
ObjectPascal

const
n = 6666;
var
p: array of biginteger;
pd: array of integer;
function PartiDiffDiff(n: Integer): Integer;
begin
if (n and 1) = 1 then result := ((n + 1) div 2)
else Result := n + 1;
end;
function partDiff(n: Integer): Integer;
begin
if n < 2 then result := 1
else begin
pd[n] := pd[n - 1] + PartiDiffDiff(n - 1);
Result := pd[n];
end;
end;
procedure partitionP(n: Integer);
begin
if n < 2 then exit;
var psum := 0bi;
for var i := 1 to n do
begin
var pdi := partDiff(i);
if pdi > n then Break;
var sign := -1bi;
if (i - 1) mod 4 < 2 then sign := 1;
psum += p[n - pdi] * sign;
end;
p[n] := psum;
end;
begin
SetLength(p, n + 1);
SetLength(pd, n + 1);
p[0] := 1bi;
pd[0] := 1;
p[1] := 1bi;
pd[1] := 1;
for var i := 2 to n do partitionP(i);
println(p[n]);
println('Took', milliseconds, 'milliseconds');
end.