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Interview Prep

In this video, given a binary tree, the task is to print the left view of the binary tree. The left view of a Binary Tree is a set of leftmost nodes for every level.&nbsp; For example:Input: &nbsp;&nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; / &nbsp;\ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;3 &nbsp; &nbsp;2 Output: 1 3 Explanation: 1 and 3 are present at the leftmost of their respective level, hence present in the output.Try it out before watching the implementation of the problem in the video. We recommend watching the video, even if you can solve the problem. You may discover something new. All the best!!!Do check out:-Article: <a href="https://www.geeksforgeeks.org/print-left-view-binary-tree/">https://www.geeksforgeeks.org/print-left-view-binary-tree/</a> Problem: h<a href="https://practice.geeksforgeeks.org/problems/left-view-of-binary-tree/1">ttps://practice.geeksforgeeks.org/problems/left-view-of-binary-tree/1</a> SDE Sheet: <a href="https://practice.geeksforgeeks.org/problems/left-view-of-binary-tree/1">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a>&nbsp;

Print Left View of Binary Tree

In this video, we will discuss the problem "Print a Binary Tree in Vertical Order". If there are multiple nodes passing through a vertical line, then they should be printed as they appear in level order traversal of the tree. The below example will explain the task at hand more thoroughly.&nbsp; Example:&nbsp; Input: &nbsp; &nbsp;&nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; / &nbsp; \ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2 &nbsp; &nbsp; &nbsp; 3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; / &nbsp; \ &nbsp; / &nbsp; \ &nbsp; &nbsp; &nbsp; &nbsp; 4 &nbsp; &nbsp; 5 6 &nbsp; &nbsp; 7 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; \ &nbsp; &nbsp; &nbsp;\ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 8 &nbsp; &nbsp; &nbsp;9Output:&nbsp; 4 2 1 5 6 3 8 7 9&nbsp; Try it out before watching the implementation of the problem in the video. We recommend watching the video, even if you can solve the problem. You may discover something new. All the best!!!Do check out:-Article: <a href="https://www.geeksforgeeks.org/print-binary-tree-vertical-order/">https://www.geeksforgeeks.org/print-binary-tree-vertical-order/</a> Problem: <a href="https://practice.geeksforgeeks.org/problems/print-a-binary-tree-in-vertical-order/1">https://practice.geeksforgeeks.org/problems/print-a-binary-tree-in-vertical-order/1</a> SDE Sheet: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> &nbsp;

Print a Binary Tree in Vertical Order

In this video, we are given a Binary Tree, The task is to print the bottom view from left to right.&nbsp; Example:Input: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;20 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;/ &nbsp; &nbsp; \ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;8 &nbsp; &nbsp; &nbsp; &nbsp; 22 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; / &nbsp; &nbsp; \ &nbsp; &nbsp; / &nbsp; &nbsp; \ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;5 &nbsp; &nbsp; &nbsp; &nbsp;3 &nbsp;4 &nbsp; &nbsp; &nbsp;25 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;/ &nbsp; &nbsp;\ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;10 &nbsp; &nbsp; &nbsp; 14 Output: 5 10 4 14 25.&nbsp; Explanation: If there are multiple bottom-most nodes for a horizontal distance from the root, then print the later one in the level traversal. 3 and 4 are both the bottom-most nodes at a horizontal distance of 0, we need to print 4.&nbsp;Try it out before watching the implementation of the problem in the video. We recommend watching the video, even if you can solve the problem. You may discover something new. All the best!!! Do check out:-Article: <a href="https://www.geeksforgeeks.org/bottom-view-binary-tree/">https://www.geeksforgeeks.org/bottom-view-binary-tree/</a> Problem: <a href="https://practice.geeksforgeeks.org/problems/bottom-view-of-binary-tree/1">https://practice.geeksforgeeks.org/problems/bottom-view-of-binary-tree/1</a> SDE Sheet: <a href="Do check out:- Article: https://www.geeksforgeeks.org/print-left-view-binary-tree/ Problem: https://practice.geeksforgeeks.org/problems/left-view-of-binary-tree/1 SDE Sheet: https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/ ">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a>&nbsp;

Print Bottom View of Binary Tree

This video is part of the Recursion and Backtracking section under GFG SDE Sheet. Imagine you have a special keyboard with the following keys:&nbsp;Key 1: &nbsp;Prints 'A' on screen Key 2: (Ctrl-A): Select screen Key 3: (Ctrl-C): Copy selection to buffer Key 4: (Ctrl-V): Print buffer on screen appending it after what has already been printed.Find maximum numbers of A's that can be produced by pressing keys on the special keyboard N times.&nbsp; Example 1:Input: N = 3
 Output: 3
 Explanation: Press key 1 three times. Try it out before watching the implementation of the problem in the video. We recommend watching the video, even if you can solve the problem. You may discover something new. All the best!!!Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/special-keyboard3018/1">https://www.geeksforgeeks.org/problems/special-keyboard3018/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/how-to-print-maximum-number-of-a-using-given-four-keys/">https://www.geeksforgeeks.org/how-to-print-maximum-number-of-a-using-given-four-keys/</a>

SDE Sheet - Special Keyboard

This video is part of the Heap section under GFG SDE Sheet. Given a string S with repeated characters. The task is to rearrange characters in a string such that no two adjacent characters are the same. Note: The string has only lowercase English alphabets and it can have multiple solutions. Return any one of them.Example 1:Input : str = "geeksforgeeks"
Output: 1
Explanation: All the repeated characters of the
given string can be rearranged so that no 
adjacent characters in the string is equal.
Any correct rearrangement will show a output
of 1.Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/rearrange-characters4649/1">https://www.geeksforgeeks.org/problems/rearrange-characters4649/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/rearrange-characters-string-no-two-adjacent/">https://www.geeksforgeeks.org/rearrange-characters-string-no-two-adjacent/</a>

SDE Sheet - Rearrange characters

This video is part of the Binary Tree section under GFG SDE Sheet. Given a binary tree in which each node element contains a number. Find the maximum possible path sum from one special node to another special node.Note: Here&nbsp;special node is a node which is connected to exactly one different node. Example 1:Input: &nbsp; &nbsp; &nbsp;
 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
 &nbsp; &nbsp; &nbsp; &nbsp; / &nbsp; &nbsp;\ &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
 &nbsp; &nbsp; &nbsp; 4 &nbsp; &nbsp; &nbsp; 5 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
 &nbsp; &nbsp; &nbsp;/ &nbsp;\ &nbsp; &nbsp; &nbsp;
 &nbsp; &nbsp;-10 &nbsp; 4 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
Output: 16
Explanation:
Maximum Sum lies between special node 4 and 5.
4 + 4 + 3 + 5 = 16. Try it out before watching the implementation of the problem in the video. We recommend watching the video, even if you can solve the problem. You may discover something new. All the best!!!Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/maximum-path-sum/1">https://www.geeksforgeeks.org/problems/maximum-path-sum/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/find-maximum-path-sum-two-leaves-binary-tree/">https://www.geeksforgeeks.org/find-maximum-path-sum-two-leaves-binary-tree/</a>

SDE Sheet - Maximum Path Sum

This video is part of the Heap section under GFG SDE Sheet. Given an array of size N. The task is to sort the array elements by completing functions heapify() and buildHeap() which are used to implement Heap Sort.Example 1:Input:
N = 5
arr[] = {4,1,3,9,7}
Output:
1 3 4 7 9
Explanation:
After sorting elements
using heap sort, elements will be
in order as 1,3,4,7,9.Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/heap-sort/1">https://www.geeksforgeeks.org/problems/heap-sort/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/heap-sort/">https://www.geeksforgeeks.org/heap-sort/</a>

SDE Sheet - Heap Sort

This video is part of the Binary Tree section under GFG SDE Sheet. Serialization is to store a tree in an array so that it can be later restored and deserialization is reading tree back from the array. Complete the functions<ul><li>serialize() :&nbsp;stores the tree into an array a and returns the array.</li><li>deSerialize() : deserializes the array to the tree and returns the root of the tree.</li></ul>Note: Multiple nodes can have the same data and the node values are always positive integers. Your code will be correct if the tree returned by deSerialize(serialize(input_tree)) is same as the input tree. Driver code will print the in-order traversal of the tree returned by deSerialize(serialize(input_tree)).Example 1:Input:
&nbsp; &nbsp;&nbsp; &nbsp;1
 &nbsp; &nbsp;/&nbsp; &nbsp;\
 &nbsp;&nbsp;2&nbsp; &nbsp;&nbsp;&nbsp;3
Output:&nbsp; 2 1 3Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/serialize-and-deserialize-a-binary-tree/1">https://www.geeksforgeeks.org/problems/serialize-and-deserialize-a-binary-tree/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/serialize-deserialize-binary-tree/">https://www.geeksforgeeks.org/serialize-deserialize-binary-tree/</a>

SDE Sheet - Serialize and Deserialize a Binary Tree

This video is part of the Linked List section under GFG SDE Sheet. Given a Linked List, where every node represents a sub-linked-list and contains two pointers: (i) a next pointer to the next node, (ii) a&nbsp;bottom&nbsp;pointer&nbsp;to a linked list where this node is head. Each of the sub-linked lists is in sorted order. Flatten the Link List so all the nodes appear in a single level while maintaining the sorted order.Note: The flattened list will be printed using the bottom pointer instead of the next pointer. Look at the printList() function in the driver code for more clarity.Examples:Input: 
Output:&nbsp; 5-&gt; 7-&gt; 8- &gt; 10 -&gt; 19-&gt; 20-&gt; 22-&gt; 28-&gt; 30-&gt; 35-&gt; 40-&gt; 45-&gt; 50.
Explanation: The resultant linked lists has every node in a single level.(Note: | represents the bottom pointer.)Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/flattening-a-linked-list/1">https://www.geeksforgeeks.org/problems/flattening-a-linked-list/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/flattening-a-linked-list/">https://www.geeksforgeeks.org/flattening-a-linked-list/</a>

SDE Sheet - Flattening a Linked List

This video is part of the Heap section under GFG SDE Sheet. Given an input stream of N integers. The task is to insert these numbers into a new stream and find the median of the stream formed by each insertion of X to the new stream.Example 1:Input:
N = 4
X[] = 5,15,1,3
Output:
5
10
5
4
Explanation:Flow in stream : 5, 15, 1, 3 
5 goes to stream --&gt; median 5 (5) 
15 goes to stream --&gt; median 10 (5,15) 
1 goes to stream --&gt; median 5 (5,15,1) 
3 goes to stream --&gt; median 4 (5,15,1 3)&nbsp;Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/find-median-in-a-stream-1587115620/1">https://www.geeksforgeeks.org/problems/find-median-in-a-stream-1587115620/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/median-of-stream-of-running-integers-using-stl/">https://www.geeksforgeeks.org/median-of-stream-of-running-integers-using-stl/</a>

SDE Sheet - Find median in a stream

This video is part of the Graph section under GFG SDE Sheet. The problem is to find the shortest distances between every pair of vertices in a given edge-weighted directed&nbsp;graph. The graph is represented as an adjacency matrix of size&nbsp;n*n. Matrix[i][j] denotes&nbsp;the weight of the edge from i to j.&nbsp;If&nbsp;Matrix[i][j]=-1,&nbsp;it means there is no&nbsp;edge from i to j. Note : Modify&nbsp;the distances&nbsp;for every pair in-place.Examples 1 :Input: matrix = [[0, 25],[-1, 0]]&nbsp; Output: [[0, 25],[-1, 0]]&nbsp; Explanation: The shortest distance between every pair is already given(if it exists). Examples 2 : Input: matrix = [[0, 1, 43],[1, 0, 6],[-1, -1, 0]]&nbsp; Output: [[0, 1, 7],[1, 0, 6],[-1, -1, 0]]&nbsp; Explanation: We can reach 2 from 0 as 0-&gt;1-&gt;2 and the cost will be 1+6=7 which is less than 43. Try it out before watching the implementation of the problem in the video. We recommend watching the video, even if you can solve the problem. You may discover something new. All the best!!!Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/implementing-floyd-warshall2042/1">https://www.geeksforgeeks.org/problems/implementing-floyd-warshall2042/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/floyd-warshall-algorithm-dp-16/">https://www.geeksforgeeks.org/floyd-warshall-algorithm-dp-16/</a>

SDE Sheet - Floyd Warshall

This video is part of the Greedy section under GFG SDE Sheet. There are N piles of coins each containing &nbsp;Ai (1&lt;=i&lt;=N) coins. Find the minimum number of coins to be removed such that the absolute difference of coins in any two piles is at most K. Note:&nbsp;You can also remove a pile by removing all the coins of that pile. Example 1:Input:
N = 4, K = 0
arr[] = {2, 2, 2, 2}
Output:
0
Explanation:
For any two piles the difference in the
number of coins is &lt;=0. So no need to
remove any coins.&nbsp;Do check out:- Problem: <a href="https://www.geeksforgeeks.org/problems/coin-piles5152/1">https://www.geeksforgeeks.org/problems/coin-piles5152/1</a> SDE Sheet Link: <a href="https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/">https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/</a> Article Link: <a href="https://www.geeksforgeeks.org/remove-minimum-coins-such-that-absolute-difference-between-any-two-piles-is-less-than-k/">https://www.geeksforgeeks.org/remove-minimum-coins-such-that-absolute-difference-between-any-two-piles-is-less-than-k/</a>

SDE Sheet - Coin Piles