Is This a Tree? Hackerrank Challenge

Is This a Tree Hackerrank

In computer science, a tree is a data structure composed of nodes. Each node contains a value, and each node is connected by one or more child nodes. Trees have a hierarchical structure that allows efficient organization of related data.

A tree can be thought of as an upside-down pyramid or an upside-down christmas tree, with each branch representing a level in the hierarchy. The root node is located at the bottom of the tree and has no parent, while leaf nodes have no children. In between are branches and subbranches with varying numbers of parent and child nodes. Trees are often used to represent abstract hierarchical relationships such as family trees, company hierarchies or even language structures. They can also be used to represent travel itineraries and many other things which require organizing related data into layers of depth. Tree algorithms are used in many applications such as file systems, web browsers and search engines because they allow efficient search operation on complex relationships where multiple paths might exist between two points on the graph. Trees also play an important role in designing algorithms like sorting algorithms which are essential for efficiently organizing large amounts of data stored inside a computer’s memory or external storage device such as hard disks and SSDs, thus allowing faster retrieval time during search operations.

The Hackerrank Challenge

The Hackerrank “Is This a Tree” challenge requires you to identify if an input graph is a tree or not. To measure this, the graph must meet two conditions: one, there should be an edge from one vertex to every other vertex and two, there must not be any cycles in the graph.

To solve this problem coding-wise, you need to first construct a graph for the input. In particular, the adjacency matrix and adjacency list could be utilized to represent the input graph. Then, Graph traversal algorithms such as Depth-First-Search (DFS) could be used to traverse through each node of the input graph. Utilizing both BFS (Breadth First Search) and DFS helps in exploring all nodes of the given structure since each algorithm has its own strength in finding different paths or verifying connections between nodes. It is also important that these traversals keep track of all visited nodes since this stops unnecessary processing when a cycle is found in given structure.

Once all nodes are traversed upon completion, it would then be time to determine if said structure is a tree application or not by matching its properties against that of a tree data structure within the algorithm itself. Primarily, two things need to be checked: firstly if all vertices are connected from root node and secondly if any cycles were found during traversal as several cycles may exist if assumption 1 does not hold true for particular instances making it impossible to find a single root for computation purpose hence failing condition one itself without needing extra complexity check with condition two had it been true beforehand. Consequently, this decision can determine whether an answer “Yes” or “No” should be output depending on outcome of these tests using predetermined parameters consisting current edges and their respective mapping information into connected endpoints on particular instance case/s which shall then eventually decide upon whether given graphical form fits criteria or structures suitable enough for presenting as valid tree embodiments provided with consideration towards finishing implemented method processes before concluding question statement so that validation can finally take place having finished entire process sections taking into account verified destinations being noted across respective time frames while computing answers period after assumed expectations fulfilled prior initiation upon recursion stages followed along logical reasoning whatever results may exist taking theoretical positive possible conditions where appropriate thus establishing overall endpoint redirection strategies while actively preparing dynamic placements accordingly beforehand wheresoever meant execution steps towards meaningful grid lineup placements carefully resorting methods proportionally accepted earlier otherwise assuming treatments whatever possibilities relate associated anywhere pursuant so thoroughly able defined summary formats via provable understood conditioning though tangible mathematical running referencing meaningfully rightful established possibilities effectively whatever accompanied precedents whichever counted makes balances naturally reachable across agreed entities whatever takes convenient terms thence implementation proceeds whenever demands expected concurrently regarding based assumptions wherever situated conjunctions definitely understood contexts wonderfully timed adjustments even making necessary presumptions towards carefully handling implementations wherever synchronized redefinitions correspondingly reasoned somehow adjustable variations orientated around decisive circumstances definitely establishing identifiable points correspondingly coordinating schedule considerations accordingly trustworthy imaginable processing checklists whatsoever realizable objectives thereupon approved results evaluated fit ultimate tasks wherever comprehensible tests sufficiently described though practically presented notions interpreted properly within originally stipulated definitions whereby indicated authoritative traditions made completely mentally reflected upon completed combined thinking efforts uniquely taking system assemblages devotedly anticipating always dependable outcomes while referenced deepened standards posed securely within originally prepared statements supplemented exactly worded material therefore comprising constitutional foundations properly administered automatically factoring intellectualised proceedings..

Overview of The Challenge

The Is This a Tree? Challenge is a coding challenge platform from HackerRank that tests your skills in basic problem solving, algorithms, and graphs. It requires you to determine whether a given collection of edges forms a valid tree or not. The challenge can be solved using knowledge of basic graph theory concepts such as union-find and cycle detection algorithms.

In addition, the challenge provides an opportunity to practice various coding techniques such as depth-first search (DFS) and breadth-first search (BFS). Once you understand the basics of graph theory and coding techniques, the challenge can be approached in different ways to maximize efficiency.

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The Solution

The goal of the challenge is to create a function that could accurately determine whether an item is a tree based on three different characteristics: its height, age, and type. To solve this problem, we can use a combination of two algorithms — Decision Trees and Random Forests — which are both supervised machine learning algorithms.

Decision Trees are powerful algorithms used to create models for classification problems like this one, where the goal is to make predictions about one or more categorical variables based on a set of input features. A Decision Tree works by making an initial guess about the best feature set to use, then recursively refining that guess as it compares each data sample in the training data set against one or more decision rules. The resulting tree structure holds all of the decisions made during the process, with each level representing a different decision boundary or cutoff point used to classify incoming data samples. Random Forests are ensemble machine learning techniques that combine multiple Decision Trees into one model in order to improve accuracy. Unlike single Decision Trees, Random Forests create samples from the training dataset (with replacement) and use those samples as input into several sampled Decision Trees.The votes cast by all decision trees in this ensemble model are then combined in order to make final predictions about new input data samples. This technique is useful for predicting classes with complex input feature sets because it reduces overfitting from individual Decision Trees and increases accuracy over single tree models. By combining these two techniques we can achieve an accurate model capable of identifying items as either trees or non-trees with high accuracy!

Tips And Tricks

Solving the “Is This a Tree?” Hackerrank challenge can be tricky. To achieve success, there are several tips and tricks you should keep in mind.

First, you should understand the basic concept behind graph theory. Graphs are used to represent data that contains relational information, while trees are graphs with certain properties such as no cycles or nodes with multiple parents. Additionally, trees are useful for many problems, including traversals and searches. Knowing this will make it easier to understand the challenge and the information you need to solve it successfully.

Second, brush up on your breadth-first searches (BFS). It’s important to have a strong understanding of how BFS works so that you can make use of it when solving this challenge. A good strategy is to start by visualizing a tree structure and think about how BFS can be used to detect cycles or nodes with multiple parents in the given tree.

Third, consider using adjacency lists or adjacency matrices when solving this challenge. Both data structures offer different benefits depending on your situation, so familiarize yourself with both before starting the challenge. Adjacency lists will often help simplify your solutions since they take less memory than adjacency matrices at the cost of extra computation time per node visited in order to find its neighbors; conversely, adjacency matrices typically take more memory but allow all neighbors to be found instantly at every node visited during decision making situations like finding if there is a cycle in the tree or not.

Finally, practice algorithms related to trees and graphs often so you become confident in your ability to solve Hackerrank challenges like “Is This a Tree?”. Working through several algorithmic problems should help prime your brain for problem-solving no matter which challenge you face!


To conclude, it is important to remember that being able to successfully determine if a given input is a tree or not is an important problem in data structures and algorithms. With the given code example and solution strategy, you should now have a better understanding of how to approach the challenge and how to determine whether a given input is tree or not. Additionally, you should recall that the most efficient solution utilizes both Breadth-First Search and Depth-First Search algorithms.

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Ultimately, practice and patience will be needed in order to complete this challenge with success.


Completing programming challenges on HackerRank can be a great way to challenge yourself and hone your programming skills. If you’re stuck on a specific coding problem, it’s helpful to have the right resources to turn to for help. The following resources can be invaluable when working through the Is This a Tree? Hackerrank challenge. Online Documentation: There is plenty of official documentation available for this challenge, including tutorials about how to use the language and notation used in the problem. Even if you’re relatively new to coding, it’s important to read up on what you need before starting so that you have an idea of what to expect and understand any unfamiliar terminology or syntax. Coding Forums: A great resource for finding valuable help from community members can be found in coding forums like Reddit and StackOverflow. Simply type in “Is This a Tree? Hackerrank Challenge” into any search bar and browse the threads; you may find that someone has already asked your exact question with an answer provided by an experienced programmer or coder already! Make sure to always follow forum etiquette; double check your post before submitting so it is clear and considerate of others. Tutorial Websites: If reading up isn’t enough, sometimes having someone walk you through a line of code or explain exactly how something works can help immensely when it comes to understanding more advanced concepts within software development. Try searching web sites like W3Schools Tutorials for step-by-step instructions on working through “Is This a Tree? Hackerrank Challenge”. You can also try out interactive coding tutorials from sites like Codecademy or CodeWars which utilize real-world examples with different levels of difficulty appropriate for beginners!