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Delete a node from a Binary Search Tree
import java.util.*;
public class DeleteNodeBST {
public static void main(String[] args) {
Node root = new Node(12);
// MAKE A TREE OF NODES...
delete(root, 14);
}
public static Node delete(Node root, int data) {
// base case, tree is empty
if (root == null) {
return root;
}
// 1.A node is in left subtree
// set root's leftchild to result of delete(root.left...)
else if (data < root.data) {
root.left = delete(root.left, data);
}
// 1.B node is in right subtree
// set root's righth child to result of delete(root.right...)
else if (data > root.data) {
root.right = delete(root.right, data);
}
// 2 found data!
else {
// Case 1: no child
// just set node to null (remove it) and return it
if (root.left == null && root.right == null) {
root = null;
}
// Case 2: one child
// 2.A: no left child
else if (root.left == null) {
Node temp = root;
root = root.right;
temp = null;
}
// 2.B: no right child
else if (root.right == null) {
Node temp = root;
root = root.left;
temp = null;
}
// Case 3: 2 children
else {
// get minimum element in right subtree
// set it to `root` and remove it from its
// original spot
Node temp = findMin(root.right);
root.data = temp.data;
root.right = delete(root.right, temp.data);
}
}
return root;
}
public static Node findMin(Node root) {
while (root.left != null)
root = root.left;
return root;
}
}
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