**Objective:** **– **Given Binary Tree, Print All The Nodes Which are X distance from the Given Node.

**Example :**

**Approach**:

Quite Tricky solution, i will explain using the example given in the picture.

**Objective:** **– **Given Binary Tree, Print All The Nodes Which are X distance from the Given Node.

**Example :**

**Approach**:

Quite Tricky solution, i will explain using the example given in the picture.

**Objective:** **– **Given nodes in a binary tree, find the distance between them.

**Example** :

**Approach****:**

**Objective:** **– **Given a inorder and postorder traversal, write an algorithm to construct a binary tree from that. This problem was asked in the Microsoft coding competition.

**Input:** Inorder and postorder traversals

**Similar Problems: Make a Binary Tree from Given Inorder and Preorder Traveral.**

**Appraoch:**

**int**[] inOrder = { 4, 2, 5, 1, 6, 3, 7 };

**int**[] postOrder = { 4, 5, 2, 6, 7, 3, 1 };.

**Objective:** **– **Find the Lowest Common Ancestor of two given nodes in a Binary Tree

*What is Lowest Common Ancestor*

*In a given binary tree, The lowest common ancestor of two nodes n1 and n2 will be a node X such that node X will be the lowest node who has n1 and n2 as its descendants.*

**Similar Problem**: Lowest Common Ancestor in a Binary Search Tree.

*Example:*

**Input:** A binary Tree and two nodes n1 and n2.

**Appraoch:**

**Objective:** **– **Given a inorder and preorder traversal, construct a binary tree from that.

**Input:** Inorder and preorder traversals

**Similar Problem: Construct a binary tree from given Inorder and Postorder Traversal**

**Approach:**

**int** [] inOrder = {2,5,6,10,12,14,15};

**int** [] preOrder = {10,5,2,6,14,12,15};

- First element in
*preorder[]*will be the*root*of the tree, here its 10. - Now the search element 10 in
*inorder[]*, say you find it at position*i*, once you find it, make note of elements which are left to*i*(this will construct the leftsubtree) and elements which are right to*i*( this will construct the rightSubtree). - See this step above and recursively construct left subtree and link it root.left and recursively construct right subtree and link it root.right.

**Objective:** Given a String, print all the permutations of it.

**Input:** A String

**Output:** Print all the permutations of a string

**Example**:

Input : abcOutput:abc acb bac bca cba cabApproach:

**Objective:** Given a binary Tree, Do Level Order Traversal in Zig Zag pattern OR Print in Spiral

**Input:** A Binary Tree

**Output: **Order Traversal in Zig Zag pattern OR Print in Spiral.

**Objective:** Given a Binary Search tree, find the inorder successor of a node.

*What is Inorder Successor: **Inorder successor of a node is the next node in the inorder traversal of the tree. For the last node in a tree, inorder successor will be NULL*

**Similar Problems : **

Inorder Successor in Binary Search Tree with parent link

Inorder Successor in Binary Tree

**Input:** A binary search tree, a node x

**Output: Inorder successor of node x.**

**Algorithms – Inorder Successor in Binary Search Tree Using Parent link**

**Objective:** Given a Binary Search tree in which every node has a link to its parent, find the inorder successor of a node.

*What is Inorder Successor: **Inorder successor of a node is the next node in the inorder traversal of the tree. For the last node in a tree, inorder successor will be NULL*

**Similar Problems :**

Inorder Successor in Binary Search Tree without parent link

Inorder Successor in Binary Tree

**Input:** A binary search tree with nodes liked to its parents, a node x

**Output: The inorder successor of node x.**

**Objective:** Given a Binary tree create Linked Lists of all the nodes at each depth , say if the tree has height k then create k linked lists.

**NOTE : This problem is very similar “Print binary tree, each level in one line“**

**Input:** A binary tree

**Output: **K linked lists if the height of tree is k. Each linked list will have all the nodes of each level.

**Example:**

**Objective:** Rearrange Positive and Negative Numbers of an Array so that one side you have positive numbers and other side with negative Integers without changing their respective order.

Example: Input : 1 -2 3 -4 5 -6 7 -8 9 -10 ReArranged Output : -2 -4 -6 -8 -10 1 3 5 7 9

**Input:** An array with positive and negative numbers

**Output:** Modified array with positive numbers and negative numbers are on each side of the array.

**Approach:**

**Method 1. **One naive approach is to have another array of same size and navigate the input array and one scan place all the negative numbers to the new array and in second scan place all the positive numbers to new array. Here the Space complexity will be O(n). We have a better solution which can solve this in O(1) space.

**Method 2: Divide and Conquer**

**Objective:** Write an algorithm to find The Longest Sequence Of Prefix Shared By All The Words In A String. This interesting problem was asked in the Google interview for software engineer. This problem is bit tricky, it looks difficult but actually it is simple problem.

**Input:** A String

**Output:** The longest sequence of prefix common in all the words in a string

**Example:**

“Bedroom BedClock BedTable BedWall” => “Bed”

**Approach:**