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In this video, we will explore how to generate all possible letter combinations from a given set of digits on a mobile keypad. The approach leverages recursion and backtracking to build combinations by appending letters corresponding to each digit in the input array. We begin by handling the base case when the prefix length matches the size of the input array, and then proceed to recursively add letters from the mapping for each digit. The digits that are invalid (0 and 1) are skipped to ensure only valid combinations are generated.Furthermore, we will demonstrate how this method works using a C++ implementation that uses a pad map to convert digits into their corresponding letters. The solution operates efficiently by appending valid letters and backtracking when necessary. The final output will be a list of all possible words that the digits could represent, such as "ad, ae, af, bd, be, bf, cd, ce, cf" for the input [2, 3]. Watch the video to see the step-by-step implementation and understand the time and space complexities involved. For more details, please go through - <a href="https://www.geeksforgeeks.org/find-possible-words-phone-digits/">Print all possible words from phone digits</a>

Print all Possible Words from Phone Digits

In this video, we will explore different approaches to solve the N-Queens problem and find all distinct solutions. We begin by discussing a naive approach that generates all possible permutations of queen placements using recursion and checks for conflicts. This method takes O(n!*n) time and O(n) space. Additionally, we delve into an expected approach using backtracking with pruning to optimize the solution by incrementally building the configuration and pruning conflicts early. This approach reduces unnecessary calculations and operates in O(n!) time and O(n) space.Furthermore, the video explains an alternate approach using bit-masking to efficiently track occupied rows and diagonals during the backtracking process. Bit-masking allows for fast bitwise operations to manage the board's state, making it particularly efficient for larger values of n. This method also runs in O(n!) time and O(n) space. Watch the video to understand these methods in detail and how they help in solving the N-Queens problem optimally with different techniques. For more details, please go through - <a href="https://www.geeksforgeeks.org/printing-solutions-n-queen-problem/">Printing all solutions in N-Queen Problem</a>

N-Queens Problem

In this video, we will explore different approaches to calculate pow(b, e) where b is the base and e is the exponent. We begin by discussing the naive iterative approach, where we multiply the base b by itself exactly e times, followed by a recursive approach to calculate power. Additionally, we delve into the expected approach, which utilizes divide and conquer for efficient calculation by halving the exponent at each step.Furthermore, the video explains how to use built-in functions in languages like C++ and Python to compute the power in optimal time complexity. By using the pow() function or the ** operator, we can quickly compute the power with minimal computational cost. Watch the video to understand these methods and their time complexities, including O(e) for naive methods and O(log e) for divide and conquer. For more details, please go through - <a href="https://www.geeksforgeeks.org/write-a-c-program-to-calculate-powxn/">Write program to calculate pow(b, e)</a>

Program to Calculate pow(b, e)

A permutation also called an “arrangement number” or “order,” is a rearrangement of the elements of an ordered list S into a one-to-one correspondence with S itself. A string of length n has n! permutation.O(n*n!) Note that there are n! permutations and it requires O(n) time to print a permutation.Write a program to print all permutations of a given string: <a href="https://www.geeksforgeeks.org/write-a-c-program-to-print-all-permutations-of-a-given-string/">https://www.geeksforgeeks.org/write-a-c-program-to-print-all-permutations-of-a-given-string/</a>

Write a program to print all permutations of a given string

We have discussed Knight’s tour and Rat in a Maze problems in Set 1 and Set 2 respectively. Let us discuss N Queen as another example problem that can be solved using backtracking.&nbsp; The N Queen is the problem of placing N chess queens on an N×N chessboard so that no two queens attack each other. For example, following is a solution for 4 Queen problem.&nbsp;N Queen Problem : <a href="https://www.geeksforgeeks.org/n-queen-problem-backtracking-3/">https://www.geeksforgeeks.org/n-queen-problem-backtracking-3/</a>

N Queen Problem

Given a partially filled 9×9 2D array ‘grid[9][9]’, the goal is to assign digits (from 1 to 9) to the empty cells so that every row, column, and subgrid of size 3×3 contains exactly one instance of the digits from 1 to 9.The naive approach is to generate all possible configurations of numbers from 1 to 9 to fill the empty cells. Try every configuration one by one until the correct configuration is found, i.e. for every unassigned position fill the position with a number from 1 to 9.&nbsp;After filling all the unassigned position check if the matrix is safe or not. If safe print else recurs for other cases. Sudoku (Visualisation) : <a href="https://www.geeksforgeeks.org/sudoku-backtracking-7/">https://www.geeksforgeeks.org/sudoku-backtracking-7/</a>

Sudoku (Visualisation)

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

Welcome to the daily solving of our PROBLEM OF THE DAY with Devashish Khare. We will discuss the entire problem step-by-step and work towards developing an optimized solution. This will not only help you brush up on your concepts of&nbsp; but also build Backtracking up problem-solving skills. Consider a rat placed at (0, 0) in a square matrix mat of order n* n. It has to reach the destination at (n - 1, n - 1). Find all possible paths that the rat can take to reach from source to destination. The directions in which the rat can move are 'U'(up), 'D'(down), 'L' (left), 'R' (right). Value 0 at a cell in the matrix represents that it is blocked and rat cannot move to it while value 1 at a cell in the matrix represents that&nbsp;rat&nbsp;can be travel&nbsp;through it. Note: In a path, no cell can be visited more than one time.&nbsp;If the source cell is 0, the rat cannot move to any other cell. In case of no path, return an empty list. The driver will output "-1" automatically.Examples:Input: mat[][] = {{1, 0, 0, 0},
 &nbsp; &nbsp; &nbsp; &nbsp; {1, 1, 0, 1}, 
 &nbsp; &nbsp; &nbsp; &nbsp; {1, 1, 0, 0},
 &nbsp; &nbsp; &nbsp; &nbsp; {0, 1, 1, 1}}
 Output:
DDRDRR DRDDRR
 Explanation:
The rat can reach the destination at 
(3, 3) from (0, 0) by two paths - DRDDRR 
and DDRDRR, when printed in sorted order 
we get DDRDRR DRDDRR. Give the problem a try before going through the video. All the best!!! Problem Link: <a href="https://practice.geeksforgeeks.org/problems-preview/rat-in-a-maze-problem/1">https://practice.geeksforgeeks.org/problems/rat-in-a-maze-problem/1</a>

PROBLEM OF THE DAY : 30/07/2024 | Rat in a Maze Problem - I

This video is part of the Recursion and Backtracking section under GFG SDE Sheet. Given a string s, remove all its adjacent duplicate characters recursively.&nbsp; Note: For some test cases, the resultant string would be an empty string. In that case, the function should return the empty string only.Example 1:Input:
S = "geeksforgeek"
 Output: "gksforgk"
 Explanation: 
g(ee)ksforg(ee)k -&gt; gksforgk 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/recursively-remove-all-adjacent-duplicates0744/1">https://www.geeksforgeeks.org/problems/recursively-remove-all-adjacent-duplicates0744/1</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/recursively-remove-adjacent-duplicates-given-string/">https://www.geeksforgeeks.org/recursively-remove-adjacent-duplicates-given-string/</a>

SDE Sheet - Recursively remove all adjacent duplicates

Explore how to find all possible paths between a given source and destination in a graph with our comprehensive tutorial. This guide is perfect for computer science students, programmers, and anyone interested in learning about graph traversal techniques and their applications in solving complex computational problems.In this tutorial, you'll learn:<ul><li>Understanding Graphs and Paths: Gain a foundational understanding of graphs, including directed and undirected graphs, and what constitutes a path in a graph. Learn about the significance of paths in various applications like network routing, circuit design, and more.</li><li>Graph Representation: Learn how to represent graphs in your program using adjacency lists or adjacency matrices, which are critical for implementing graph traversal algorithms.</li><li>Using Depth-First Search (DFS): Detailed instructions on implementing the Depth-First Search (DFS) algorithm to explore all possible paths between two nodes. Understand how DFS traverses a graph by exploring as far as possible along each branch before backtracking, which makes it ideal for finding paths.</li><li>Implementing Backtracking: Step-by-step guide on using backtracking with DFS to ensure all paths are considered and to avoid visiting the same node twice in the same path. This section will cover how to manage path lists and avoid cycles in the paths.</li><li>Breadth-First Search (BFS) Consideration: Discussion on when BFS might be used instead of DFS, particularly when looking for the shortest path in unweighted graphs, although the primary focus will be on using DFS for finding all paths.</li><li>Code Examples: Practical coding examples in popular programming languages like Python, Java, or C++ demonstrating how to implement these algorithms to find all paths between two nodes.</li><li>Complexity Analysis: Analyze the time and space complexities of your solutions, providing insights into the computational efficiency and potential scalability issues.</li><li>Applications and Real-World Examples: Explore real-world applications of finding paths in graphs, such as in social network analysis, logistics, and transportation planning.</li><li>Advanced Techniques: Introduction to more advanced techniques and algorithms for pathfinding in graphs, including Dijkstra’s and Floyd-Warshall algorithms for situations involving weighted paths.</li></ul>By the end of this tutorial, you’ll have a thorough understanding of how to find all paths between two nodes in a graph, enhancing your ability to solve problems that require an in-depth understanding of graph traversal techniques.For a comprehensive guide on finding paths from a given source to a destination in a graph, including detailed code examples and discussions on optimizing your algorithms, check out our full article at <a href="https://www.geeksforgeeks.org/find-paths-given-source-destination/">https://www.geeksforgeeks.org/find-paths-given-source-destination/</a>.This tutorial will not only bolster your graph theory and algorithm skills but also prepare you to tackle complex problems involving network analysis and pathfinding in various fields of computing and engineering.

Count the paths | DSA Problem

Learn how to solve the "Combination Sum" problem with our comprehensive tutorial. This guide is invaluable for programmers and algorithm enthusiasts seeking to master the techniques of generating combinations that sum up to a target value efficiently.In this tutorial, you'll explore:<ul><li style="margin-left:0px;">Problem Overview: Understand the essence of the Combination Sum problem, which involves finding all unique combinations in a set of candidates that sum up to a given target value.</li><li style="margin-left:0px;">Algorithmic Approach: Dive into the algorithmic strategies used to tackle the Combination Sum problem, including backtracking and depth-first search (DFS).</li><li style="margin-left:0px;">Step-by-Step Implementation: Follow along with detailed step-by-step explanations of how to implement the algorithm to generate combinations that meet the target sum requirements.</li><li style="margin-left:0px;">Coding Examples: Explore practical coding examples in popular programming languages such as Python, Java, and C++, providing you with hands-on experience in solving the Combination Sum problem.</li><li style="margin-left:0px;">Complexity Analysis: Gain insights into the time and space complexities of the algorithm, allowing you to evaluate its efficiency and scalability for different input scenarios.</li></ul>By mastering the techniques presented in this tutorial, you'll sharpen your problem-solving skills and be well-equipped to tackle a wide range of combinatorial problems effectively.For a deep dive into solving the Combination Sum problem, complete with detailed explanations and code examples, check out the full article at <a href="https://www.geeksforgeeks.org/combinational-sum/">https://www.geeksforgeeks.org/combinational-sum/</a>.This tutorial will empower you to confidently approach combinatorial problems and devise efficient solutions, enabling you to excel in algorithmic programming challenges and real-world applications alike.

Combination Sum | DSA Problem

Embark on a journey into algorithmic problem-solving and uncover the techniques for finding the shortest safe route in a path with landmines with our comprehensive tutorial! Whether you're new to graph algorithms or seeking to enhance your problem-solving skills, understanding how to navigate paths with obstacles is essential for various scenarios, including navigation and optimization problems.In this tutorial, we'll explore the concept of finding the shortest safe route in a path with landmines. You'll learn about the challenges posed by landmines and how to overcome them using algorithms such as breadth-first search (BFS) or Dijkstra's algorithm to find the shortest path while avoiding unsafe areas.Join us as we delve into the intricacies of algorithmic problem-solving, providing practical examples, code snippets, and algorithmic insights along the way. From understanding the problem statement to implementing the optimal solution step by step, you'll gain the skills to tackle similar challenges with confidence.Ready to master algorithmic problem-solving and navigate paths with landmines? Dive into our tutorial now and discover how to solve this challenging problem like a pro! For further exploration and detailed insights, don't forget to peruse the accompanying article on GeeksforGeeks: <a href="https://www.geeksforgeeks.org/find-shortest-safe-route-in-a-path-with-landmines/">https://www.geeksforgeeks.org/find-shortest-safe-route-in-a-path-with-landmines/</a>Don't miss out on the opportunity to elevate your algorithmic skills and conquer pathfinding challenges. Like, share, and subscribe for more tutorials and insights into algorithmic concepts. Let's find safe routes together. Happy coding!

Find shortest safe route in a matrix | DSA Problem

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