Data update

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

@@ -0,0 +1,48 @@
+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.