With this code I'm having trouble writing the "remove" function for the AVL Tree utilizing the below Binary Node Class I created (BinNode). How would I get the "remove" method to work? Or how would I replace it? @Override public void remove(String data) {this.setRoot(remove(this.getRoot(), data));} I keep getting an error and not sure why or how to fix. Would it be possible to help with recreating the AVL Remove Function or fix this issue?
With this code I'm having trouble writing the "remove" function for the AVL Tree utilizing the below Binary Node Class I created (BinNode). How would I get the "remove" method to work? Or how would I replace it?
@Override
public void remove(String data) {this.setRoot(remove(this.getRoot(), data));}
I keep getting an error and not sure why or how to fix. Would it be possible to help with recreating the AVL Remove Function or fix this issue?
Binary Node Class
public class BinNode
{
private String data;
private BinNode left;
private BinNode right;
private int height; //height field as with AVL tree or Red Black Tree
private boolean color; //Needed for Red Black Tree
public BinNode(){
data = "";
left = null;
right = null;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
public BinNode(String d){
data = d;
left = null;
right = null;
}
public void setData(String d){
this.data = d;
}
public String getData(){
return this.data;
}
public void setLeft(BinNode l){
this.left = l;
}
public BinNode getLeft(){
return this.left;
}
public void setRight(BinNode r){
this.right = r;
}
public BinNode getRight(){
return this.right;
}
}
AVL Tree I built
public class AVLTree extends BinaryTree{
@Override
public void insert(String data) {
this.setRoot(insert(this.getRoot(), data));
}
private BinNode insert(BinNode node, String data) {
if (node == null) {
return new BinNode(data);
} else {
int i = node.getData().compareTo(data);
if (i < 0) {
node.setRight(insert(node.getRight(), data));
} else if (i >= 0) {
node.setLeft(insert(node.getLeft(), data));
}
// Update the height of the current node
int leftHeight = height(node.getLeft());
int rightHeight = height(node.getRight());
node.setHeight(1 + Math.max(leftHeight, rightHeight));
int balance = getBalance(node);
if (balance > 1) {
if (data.compareTo(node.getLeft().getData()) < 0) {
return rightRotate(node);
} else {
// Left-Right case
node.setLeft(leftRotate(node.getLeft()));
return rightRotate(node);
}
}
if (balance < -1) {
if (data.compareTo(node.getRight().getData()) > 0) {
// Right-Right case
return leftRotate(node);
} else {
// Right-Left case
node.setRight(rightRotate(node.getRight()));
return leftRotate(node);
}
}
return node;
}
}
private int height(BinNode node) {
if (node == null) {
return 0;
}
return node.getHeight();
}
private int getBalance(BinNode node) {
if (node == null) {
return 0;
}
return height(node.getLeft()) - height(node.getRight());
}
private BinNode rightRotate(BinNode y) {
BinNode x = y.getLeft();
BinNode T2 = x.getRight();
// Perform rotation
x.setRight(y);
y.setLeft(T2);
y.setHeight(Math.max(height(y.getLeft()), height(y.getRight())) + 1);
x.setHeight(Math.max(height(x.getLeft()), height(x.getRight())) + 1);
return x;
}
private BinNode leftRotate(BinNode x) {
BinNode y = x.getRight();
BinNode T2 = y.getLeft();
// Perform rotation
y.setLeft(x);
x.setRight(T2);
x.setHeight(Math.max(height(x.getLeft()), height(x.getRight())) + 1);
y.setHeight(Math.max(height(y.getLeft()), height(y.getRight())) + 1);
return y;
}
/* Don't know why this doesn't work
@Override
public void remove(String data) {this.setRoot(remove(this.getRoot(), data));}
*/
public BinNode remove(BinNode root, String data) {
// Step 1 - Perform standard BST delete
if (root == null) {
return root;
}
int cmp = data.compareTo(root.getData());
if (cmp < 0) {
root.setLeft(remove(root.getLeft(), data));
} else if (cmp > 0) {
root.setRight(remove(root.getRight(), data));
} else {
// node with only one child or no child
if ((root.getLeft() == null) || (root.getRight() == null)) {
BinNode temp = null;
if (temp == root.getLeft()) {
temp = root.getRight();
} else {
temp = root.getLeft();
}
// No child case
if (temp == null) {
temp = root;
root = null;
} else { // One child case
root = temp; // Copy the contents of the non-empty child
}
} else {
// node with two children: get the inorder successor (smallest in the right subtree)
BinNode temp = minValueNode(root.getRight());
// copy the inorder successor's data to this node
root.setData(temp.getData());
root.setRight(remove(root.getRight(), temp.getData()));
}
}
// if the tree had only one node then return
if (root == null) {
return root;
}
// Step 2 - Update the height of the current node
root.setHeight(Math.max(height(root.getLeft()), height(root.getRight())) + 1);
// Step 3 - Get the balance factor
int balance = getBalance(root);
// Step 4 - If the node is unbalanced, then try out the 4 cases
// Left Left Case
if (balance > 1 && getBalance(root.getLeft()) >= 0) {
return rightRotate(root);
}
// Right Right Case
if (balance < -1 && getBalance(root.getRight()) <= 0) {
return leftRotate(root);
}
// Left Right Case
if (balance > 1 && getBalance(root.getLeft()) < 0) {
root.setLeft(leftRotate(root.getLeft()));
return rightRotate(root);
}
// Right Left Case
if (balance < -1 && getBalance(root.getRight()) > 0) {
root.setRight(rightRotate(root.getRight()));
return leftRotate(root);
}
return root;
}
private BinNode minValueNode(BinNode node) {
BinNode current = node;
/* loop down to find the leftmost leaf */
while (current.getLeft() != null) {
current = current.getLeft();
}
return current;
}
}
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