8000 tree questions · Ismail0290/DSA-Bootcamp-Java@ffbe275 · GitHub
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kunal-kushwahakunal-kushwaha
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tree questions
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‎lectures/20-trees/code/Advance questions/DoubleLinkedList.java

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public class DoubleLinkedList {
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LLNode head;
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LLNode tail;
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public TreeNode convert(TreeNode root) {
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if (root == null) {
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return null;
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}
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helper(root);
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return head;
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}
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private void helper(TreeNode node) {
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if(node == null) {
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return null;
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}
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helper(node.left);
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LLNode newNode = new LLNode(node.val);
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if(head == null) {
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head = newNode;
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tail = newNode;
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} else {
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tail.next = newNode;
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newNode.prev = tail;
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tail = newNode;
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}
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helper(node.right);
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}
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}
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class LLNode {
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int val;
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LLNode prev;
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LLNode next;
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public LLNode (int val) {
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this.val = val;
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}
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}
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class TreeNode {
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int val;
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TreeNode left;
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TreeNode right;
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public TreeNode (int val) {
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this.val = val;
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}
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}

‎lectures/20-trees/code/Advance questions/TwoNodeSwap.java

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import java.util.*;
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class Node {
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int val;
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Node left;
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Node right;
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public Node (int val) {
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this.val = val;
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}
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}
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public class TwoNodeSwap {
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Node first;
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Node second;
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Node prev;
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public void helper(Node root) {
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iot(root);
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// swap
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int temp = first.val;
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first.val = second.val;
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second.val = temp;
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}
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private void iot(Node node) {
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if(node == null) {
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return;
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}
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iot(node.left);
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if(prev != null && prev.val > node.val) {
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if(first == null) {
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first = prev;
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}
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second = node;
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}
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prev = node;
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iot(node.right);
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}
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public void printIOT(Node node) {
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if(node == null) {
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return;
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}
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printIOT(node.left);
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System.out.print(node.val + " ");
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printIOT(node.right);
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}
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}

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