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Re-Written Delete method on Binary Tree

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This commit is contained in:
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 //Delete Item (replace) and replace pointers to retain integrity of tree
TreeNode<T>? node = deletionStack.Pop(); 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 to store the items leading up to the value that we will use to replace the node
Stack<TreeNode<T>>? replacementStack = Min(node!.Right); 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(); TreeNode<T>? replacementNode = replacementStack.Pop();
node.Value = replacementNode!.Value; switch (replacementStack.GetCount())
{//Determine what to do based on number of items in replacement stack
//Remove the node that we have taken the value from case 1:
if (replacementStack.Peek() != default) node.Right = replacementNode!.Right;
{//If the parent is not the node that we replaced break;
replacementStack.Pop()!.Left = replacementNode.Right; case >=2:
}else{//If the parent is the node what we replaced replacementStack.Peek()!.Left = replacementNode!.Right;
node.Right = replacementNode.Right; break;
} default:
}else{ break;
//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;
} }
} }
Count--; Count--;

10
C#/Program.cs
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@ -112,15 +112,17 @@ Console.WriteLine("Hello, World!");
Tree<int> tree = new Tree<int>(); Tree<int> tree = new Tree<int>();
tree.Add(5); tree.Add(10);
tree.Add(4); tree.Add(8);
tree.Add(6);
tree.Add(3); tree.Add(3);
tree.Add(4);
tree.Add(5);
tree.Add(2); tree.Add(2);
tree.Add(1);
tree.Add(0); tree.Add(0);
var x = tree.Delete(3); var x = tree.Delete(10);
//tree.Delete(5); //tree.Delete(5);
var l = tree.Inorder(null); var l = tree.Inorder(null);