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Merge branch 'main' of github.com:princomp/princomp.github.io
2 parents 7c71871 + 7cee230 commit ad18a15

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26 files changed

+1537
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‎source/code/projects/AVLTree_I_solution/AVLTree/AVLTree.cs‎

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using System;
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using System.Collections.Generic;
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public class AVLTree<T> : BSTree<T>
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where T : IComparable<T>
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{
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public override void Insert(T valueP)
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{
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root = Insert(valueP, root);
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}
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private Node Insert(T valueP, Node nodeP)
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{
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if (nodeP == null)
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return new Node(valueP, null, null);
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else if (valueP.CompareTo(nodeP.Data) < 0) // valueP < nodeP.Data --> go left
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{
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nodeP.left = Insert(valueP, nodeP.left);
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int nodePLH =
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(nodeP.left == null) ? -1 : nodeP.left.Height;
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int nodePRH =
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(nodeP.right == null) ? -1 : nodeP.right.Height;
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if (nodePLH - nodePRH == 2)
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{
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if (valueP.CompareTo(nodeP.left.Data) < 0)
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{
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nodeP = RotateleftChild(nodeP);
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}
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else
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{
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nodeP = DoubleleftChild(nodeP);
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}
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}
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}
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else if (valueP.CompareTo(nodeP.Data) > 0) // valueP > nodeP.Data --> go right
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{
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nodeP.right = Insert(valueP, nodeP.right);
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int nodePLH =
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(nodeP.left == null) ? -1 : nodeP.left.Height;
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int nodePRH =
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(nodeP.right == null) ? -1 : nodeP.right.Height;
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if (nodePRH - nodePLH == 2)
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{
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if (valueP.CompareTo(nodeP.right.Data) > 0)
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{
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nodeP = RotaterightChild(nodeP);
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}
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else
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{
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nodeP = DoublerightChild(nodeP);
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}
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}
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}
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else // valueP == nodeP.Data
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{
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throw new ApplicationException(
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"Tree did not insert "
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+ valueP
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+ " since an item with that value is already in the tree"
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);
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}
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return nodeP;
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}
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public override bool Delete(T dataP)
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{
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return Delete(dataP, ref root);
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}
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private bool Delete(T value, ref Node nodeP)
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{
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bool found = false;
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if (nodeP != null)
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{
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if (value.CompareTo(nodeP.Data) < 0) // value < nodeP.Data, check left subtree
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{
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found = Delete(value, ref nodeP.left); // similar to BST's find and remove method
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if (SubtreeBalance(nodeP) <= -2) // negative balance means heavy on right side
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{
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if (SubtreeBalance(nodeP.right) <= 0) // children in straight line
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nodeP = RotaterightChild(nodeP); // rotate middle up to balance
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else
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nodeP = DoublerightChild(nodeP); // children in zig patter - needs double rotate to balance
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}
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}
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else if (value.CompareTo(nodeP.Data) > 0) // value > nodeP.Data, check right subtree
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{
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found = Delete(value, ref nodeP.right);
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if (SubtreeBalance(nodeP) >= 2)
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{
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if (SubtreeBalance(nodeP.left) >= 0)
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nodeP = RotateleftChild(nodeP);
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else
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nodeP = DoubleleftChild(nodeP);
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}
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}
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else // The value was found!
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{
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found = true;
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if (nodeP.left != null && nodeP.right != null) // Two children
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{
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nodeP.Data = FindMin(nodeP.right);
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Delete(nodeP.Data, ref nodeP.right);
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if (SubtreeBalance(nodeP) == 2) // Need to rebalance
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{
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if (SubtreeBalance(nodeP.left) >= 0)
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nodeP = RotateleftChild(nodeP);
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else
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nodeP = DoubleleftChild(nodeP);
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}
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}
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else
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{
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nodeP = nodeP.left ?? nodeP.right; // replace with one or no child
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// This is equivalent to
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// if (nodeP.left == null){
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// nodeP = nodeP.right;
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// } else { nodeP = nodeP.left;}
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// Observe that if both are null, then nodeP simply
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// becomes null, as expected.
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}
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}
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}
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return found;
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}
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}

‎source/code/projects/AVLTree_I_solution/AVLTree/BSTree.cs‎

Lines changed: 147 additions & 0 deletions
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using System;
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using System.Collections.Generic;
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public class BSTree<T> : IBTree<T>
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where T : IComparable<T>
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{
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// Inserting into a BSTree
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public override void Insert(T dataP)
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{
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root = Insert(dataP, root);
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}
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private Node Insert(T dataP, Node nodeP)
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{
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if (nodeP == null)
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{
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return new Node(dataP, null, null);
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}
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else if (dataP.CompareTo(nodeP.Data) < 0) // dataP < nodeP.Data
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{
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nodeP.left = Insert(dataP, nodeP.left);
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}
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else if (dataP.CompareTo(nodeP.Data) > 0) // dataP > nodeP.Data
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{
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nodeP.right = Insert(dataP, nodeP.right);
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}
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else
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{
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throw new ApplicationException(
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"Value " + dataP + " already in tree."
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);
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}
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return nodeP;
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}
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// Finding into a BSTree
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public override bool Find(T dataP)
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{
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bool found = false;
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if (root != null)
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{
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found = Find(dataP, root);
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}
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return found;
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}
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private bool Find(T dataP, Node nodeP)
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{
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bool found = false;
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if (nodeP != null)
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{
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if (nodeP.Data.Equals(dataP))
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{
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found = true;
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}
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else
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{
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if (dataP.CompareTo(nodeP.Data) < 0) // dataP < nodeP.Data
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{
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found = Find(dataP, nodeP.left);
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}
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else if (dataP.CompareTo(nodeP.Data) > 0) // dataP > nodeP.Data
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{
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found = Find(dataP, nodeP.right);
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}
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}
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}
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return found;
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}
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public T FindMin()
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{
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if (root == null)
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{
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throw new ApplicationException(
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"Cannot find a value in an empty tree!"
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);
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}
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else
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{
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return FindMin(root);
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}
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}
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protected T FindMin(Node nodeP)
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{
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T minValue;
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if (nodeP.left == null)
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{
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minValue = nodeP.Data;
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}
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else
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{
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minValue = FindMin(nodeP.left);
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}
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return minValue;
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}
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// Deleting from a BSTree
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public override bool Delete(T dataP)
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{
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return Delete(dataP, ref root);
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}
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private bool Delete(T dataP, ref Node nodeP)
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{
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bool found = false;
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if (nodeP != null)
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{
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if (dataP.CompareTo(nodeP.Data) < 0) // dataP < nodeP.Data
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{
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found = Delete(dataP, ref nodeP.left);
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}
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else if (dataP.CompareTo(nodeP.Data) > 0) // dataP > nodeP.Data
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{
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found = Delete(dataP, ref nodeP.right);
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}
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else // We found the value!
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{
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found = true;
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if (nodeP.left != null && nodeP.right != null)
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{
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nodeP.Data = FindMin(nodeP.right);
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Delete(nodeP.Data, ref nodeP.right);
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// Or we could replace with the largest
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// value in the left subtree.
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}
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else
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{
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if (nodeP.left != null)
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{
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nodeP = nodeP.left;
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}
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else
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{
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nodeP = nodeP.right;
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}
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}
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}
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}
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return found;
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}
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// Done with deletion.
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}

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