Data update

Task/Dutch-national-flag-problem/PascalABC.NET/dutch-national-flag-problem.pas

@@ -0,0 +1,33 @@
+type
+  colors = (red, white, blue);
+
+procedure threeWayPartition(a: array of colors; mid: colors);
+begin
+  var (i, j) := (0, 0);
+  var k := a.High;
+  while j <= k do
+    if a[j] < mid then
+    begin
+      swap(a[i], a[j]);
+      i += 1;
+      j += 1;
+    end
+    else if a[j] > mid then
+    begin
+      swap(a[j], a[k]);
+      k -= 1;
+    end
+    else j += 1;
+end;
+
+begin
+  var balls: array of colors;
+  repeat
+    balls := ArrGen(10, i -> |red, white, blue|.randomelement);
+  until balls <> balls.Sorted;
+
+  println('Original ball order:', balls);
+  threewaypartition(balls, white);
+  println('Sorted ball order:  ', balls);
+  assert(balls <> balls.sorted, 'Not sorted!');
+end.