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Re-Written Delete method on Binary Tree

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Luke Else
2022-04-17 23:14:18 +01:00
parent 6ae360f3bc
commit 564e4d161f
2 changed files with 33 additions and 24 deletions
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47
C#/Datastructures/BinaryTree/Tree.cs
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@@ -78,31 +78,38 @@ namespace C_.Datastructures.BinaryTree
//Delete Item (replace) and replace pointers to retain integrity of tree
TreeNode<T>? node = deletionStack.Pop();
TreeNode<T>? parent = deletionStack.Pop();
//stack to store the items leading up to the value that we will use to replace the node
Stack<TreeNode<T>>? replacementStack = Min(node!.Right);
if (replacementStack != default)
{//If there are values to the right
if (replacementStack == default)
{//Nothing to the right of the value we are deleting
if (deletionStack.Peek() != default)
{//Parent adopts left hand side of node if present
deletionStack.Pop()!.Left = node.Left;
}
if (node.Left != default)
{//Node adopts left value if no lower value to the right
node.Value = node.Left!.Value;
node.Left = node.Left.Left;
}
}
else
{//Replace the value + reorder nodes
node.Value = replacementStack.Peek()!.Value;
TreeNode<T>? replacementNode = replacementStack.Pop();
node.Value = replacementNode!.Value;
//Remove the node that we have taken the value from
if (replacementStack.Peek() != default)
{//If the parent is not the node that we replaced
replacementStack.Pop()!.Left = replacementNode.Right;
}else{//If the parent is the node what we replaced
node.Right = replacementNode.Right;
}
}else{
//Parent's relation needs to be set to null as there are no greater values
if (node.Value!.CompareTo(parent!.Value) < 0)
{//Item being deleted is the left child
parent.Left = default;
}else{
//Item being deleted is the right value
parent.Right = default;
switch (replacementStack.GetCount())
{//Determine what to do based on number of items in replacement stack
case 1:
node.Right = replacementNode!.Right;
break;
case >=2:
replacementStack.Peek()!.Left = replacementNode!.Right;
break;
default:
break;
}
}
Count--;