// Make a list of random items.
private void makeItemsButton_Click(object sender, EventArgs e)
{
int numItems = int.Parse(numItemsTextBox.Text);
int minimum = int.Parse(minimumTextBox.Text);
int maximum = int.Parse(maximumTextBox.Text);
Random rand = new Random();
// Delete the previous list if there is one.
//(This isn't necessary in C#.)
// Add cells.
ValueCell newTop = null;
for (int i = 0; i < numItems; i++)
{
ValueCell newCell = new ValueCell();
newCell.Value = rand.Next(minimum, maximum);
newCell.Next = newTop;
newTop = newCell;
}
// Make a new sentinel.
TopCell = new ValueCell()
{
Value = 0, Next = newTop
};
// Make a copy.
CopyTopCell = TopCell.CopyList();
// Display the list.
DisplayList();
}
// Use insertionsort to sort the list after this cell.
// (This assumes we are the sentinel.)
public void Insertionsort()
{
// Make a sentinel for the new list.
ValueCell newTop = new ValueCell()
{
Next = null
};
// Repeat until the list is empty.
while (this.Next != null)
{
// Remove the next cell from the original list.
ValueCell cell = this.Next;
int cellValue = cell.Value;
this.Next = cell.Next;
// Insert it in the new list.
for (ValueCell before = newTop; ; before = before.Next)
{
// If before.Next is null or the next
// cell's value >= this one, insert the item here.
if ((before.Next == null) || (before.Next.Value >= cellValue))
{
// Insert the new value after before.
cell.Next = before.Next;
before.Next = cell;
break;
}
}
}
// Make this cell be the sentinel for the new list.
this.Next = newTop.Next;
}
// Make a copy of the list (non-recursively).
public ValueCell CopyList()
{
// Make a new top for the list.
ValueCell newTop = new ValueCell();
newTop.Value = this.Value;
// Make a cell to hold the last cell in the new list.
ValueCell lastCell = newTop;
// Make the other cells.
for (ValueCell cell = this.Next; cell != null; cell = cell.Next)
{
// Make the new cell.
ValueCell newCell = new ValueCell();
newCell.Value = cell.Value;
// Add it to the list.
lastCell.Next = newCell;
lastCell = newCell;
}
// End the list.
lastCell.Next = null;
// Return the copy.
return(newTop);
}
// Display the items.
private void DisplayList()
{
valueListBox.Items.Clear();
int i = 0;
for (ValueCell cell = TopCell.Next; cell != null; cell = cell.Next)
{
valueListBox.Items.Add(cell.Value);
// Only list up to 1000 items.
if (++i > 1000)
{
break;
}
}
}
// Verify that the list below this item is sorted (non-recursively).
public bool IsSorted()
{
// An empty list is sorted.
if (this.Next == null)
{
return(true);
}
for (ValueCell cell = this.Next; cell.Next != null; cell = cell.Next)
{
if (cell.Value > cell.Next.Value)
{
return(false);
}
}
// If we get this far, the list is sorted.
return(true);
}
// Use selectionsort to sort the list after this cell.
// (This assumes we are the sentinel.)
public void Selectionsort()
{
// Make a new top cell reference.
// Note that the new list doesn't have a sentinel.
ValueCell newTop = null;
// Repeat until the list is empty.
while (this.Next != null)
{
// Find the next biggest value in the list.
ValueCell bestBefore = this;
int bestValue = bestBefore.Next.Value;
// Search the other cells to find a bigger value.
for (ValueCell cell = bestBefore.Next; cell.Next != null; cell = cell.Next)
{
// See if the next cell's value is bigger than
// the biggest value we've found so far.
if (cell.Next.Value > bestValue)
{
// Replace the biggest value found.
bestValue = cell.Next.Value;
bestBefore = cell;
}
}
// Remove the best cell from the old list.
ValueCell bestCell = bestBefore.Next;
bestBefore.Next = bestCell.Next;
// Add the cell to the top of the new list.
bestCell.Next = newTop;
newTop = bestCell;
}
// Make this cell be the sentinel for the new list.
this.Next = newTop;
}
// Reset the list to the original insorted values.
private void resetButton_Click(object sender, EventArgs e)
{
TopCell = CopyTopCell.CopyList();
DisplayList();
}
