Questions tagged [depth-first-search]

Depth-first search (DFS) is an algorithm for traversing or searching tree or graph data structures. One starts at the root (selecting some node as the root in the graph case) and explores as far as possible along each branch before backtracking.

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3
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1answer
48 views

Creating valid words on an n-by-n grid of characters using depth-first search

I am trying to create a word-finder game. There will be an n-by-n Board filled with Tiles. ...
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41 views

A generic DFS in JavaScript

I implemented a general function for a depth-first-search (DFS) using JavaScript with default arguments and functions that need to be provided in order for it to work. This function is using ...
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1answer
53 views

Find the lengths of strongly connected components in a graph

I wrote a code to calculate the lengths of strongly connected components in a graph. The results I get are correct but it scales horribly. This is the code I have. I understand that the runtime ...
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534 views

LeetCode: critical connections in a network C# (Tarjan's algorithm)

https://leetcode.com/problems/critical-connections-in-a-network/ Please review for memory and runtime performance. There are n servers numbered from 0 to n-1 connected by undirected server-to-...
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2answers
113 views

Optimize depth-first search for sliding tile puzzle

My current code implementing a depth-first search works well for puzzle 1. But my code is too slow; I think I use too many loops and I am not sure I am using the right data structure. So I have a ...
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1answer
65 views

Maze path finder using Depth-First Search algorithm

I'm trying to resolve this kata from CodeWars. Kata exercise You are at position [0, 0] in maze NxN and you can only move in one of the four cardinal directions (i.e. North, East, South, West). ...
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1answer
42 views

Javascript Tree Class 2

This question is the second version of the code here. I'm writing a general tree class. Specifically, each node should have oen parent, some number of children, and hold a value. I'm looking for ...
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2answers
74 views

Javascript Tree Class

I got caught in the trap of implementing my own data structure. I've created a very general tree structure, where each node gets one parent, some children, and holds a value. I'm mostly looking for ...
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2answers
148 views

Ruby implementation for Hacker Rank connected cells in a grid

https://www.hackerrank.com/challenges/connected-cell-in-a-grid/problem problem statement: Consider a matrix where each cell contains either a 1 or a 0. Any cell containing a 1 is called a ...
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1answer
46 views

Find articulation points/ cut vertices in graph

I would like to get some feedback on my completed code that finds and displays the articulation vertices in an undirected graph. I included a test case within the code, it should (and does) print <...
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0answers
54 views

Graph-coloring solution using depth-first search

I'm trying to solve this question: Andryusha goes through a park each day. The squares and paths between them look boring to Andryusha, so he decided to decorate them. The park consists of n ...
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2answers
74 views

Finding a vertex of a tree such that every subtree rooted at that vertex is of a uniform color

I'm trying to optimally solve codeforces problem 763A: Each New Year Timofey and his friends cut down a tree of n vertices and bring it home. After that they paint all the n its vertices, so ...
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2answers
166 views

Find all possible words in a board of characters

This question has 2 possible solutions and I am trying to implement the DFS solution. Here is the Trie and DFS solution: Boggle using Trie and DFS Please review for performance. Given a ...
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1answer
94 views

(Leetcode) Freedom Trail

I would like to know whether I could make my solution to this challenge shorter and more efficient. Below is the description of the challenge (this is a Leetcode problem) - In the video game ...
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2answers
209 views

(Leetcode) Minesweeper game

This is a Leetcode problem - Let's play the Minesweeper game (Wikipedia, online game)! You are given a 2D char matrix representing the game board. 'M' represents an unrevealed mine, 'E' ...
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1answer
65 views

(Leetcode) 24 game in Python

This is a Leetcode problem - You have 4 cards each containing a number from 1 to 9. You need to judge whether they could be ...
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1answer
144 views

LeetCode: Add and Search Word C#

This is a Leetcode problem: Design a data structure that supports the following two operations: void addWord(word) ...
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1answer
154 views

Find all concatenated words in a given list of words

This is a Leetcode problem - Given a list of words (without duplicates), write a program that returns all concatenated words in the given list of words. A concatenated word is defined as a ...
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2answers
74 views

Leetcode: Flatten binary tree to linked list C#

https://leetcode.com/problems/flatten-binary-tree-to-linked-list/ Please comment on performance Given a binary tree, flatten it to a linked list in-place. For example, given the following ...
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1answer
161 views

Return all valid paren strings with a given length

The problem is Given a non-negative integer n, return all valid parentheses strings with n open parens and ...
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1answer
57 views

Find number of islands Leetcode

Here is the question: Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally ...
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1answer
979 views

Java Maze Solver (DFS)

I was asked to create a Java program that will navigate through a series of mazes. I would like to know if this is the optimal way of using a DFS or is there a better way and I am doing something ...
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42 views

Choose numbers from a grid, minimising the sum

Given a 2-D input matrix, I need to pick elements from it. constraint: you can pick one number at each row, each column given: number boards are given expected output: print least sum of ...
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1answer
58 views

Find the longest connect cells region per color

I have been studying graphs/BFS/DFS. working on wrapping my head around the following problem Given a grid [m,n] where each cell has a value denotes a color, find the longest connected region that ...
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I have written two versions of Word Break exhaustive combinations. Please comment

I am solving Word Break II from leetcode. https://leetcode.com/problems/word-break-ii/description/ Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, add ...
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Generating the powerset in C

I am solving another problem in leetcode. Given a set, generate all the subsets of the set. Input: [1,2,3] Output: ...
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1answer
581 views

Count number of islands 2d grid

This is a recursive approach using DFS to counting the number of islands. However, I would like to improve performance, while keeping the code clean concise and readable. Better yet can this be solved ...
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0answers
68 views

DFS logic to traverse a graph

I tried to literally convert recursive algorithm taught here to iterative, by simulating the recursive stack exactly as much as possible. I have tested my code and it passed all test cases. Please ...
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1answer
5k views

Searching a maze using DFS and BFS in Python 3

I solved the problem posted from Make School Trees and Maze article, which asks me to searching a maze using DFS and BFS in Python. Here's the final output from PyGame: I would like to ask for code ...
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0answers
529 views

Max flow Ford-Fulkerson using DFS augmented path retrieval

I have written a naive max flow with DFS, could anyone review my below code. What can be done to improve the code and what are the worst cases where this won’t work acceptably? ...
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1answer
1k views

Depth First Search of graph in Python

Task: Do DFS traversal from a given given graph and print output. Is this code the correct implementation of DFS traversal in Graph? ...
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2answers
2k views

DFS in a binary tree

Problem statement: Perform a depth first traversal on a BST and print the elements traversed. ...
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1answer
554 views

Cheapest flights with at most k stops

This is the Cheapest Flights Within K Stops problem from leetcode.com: There are \$n\$ cities connected by \$m\$ flights. Each fight starts from city \$u\$ and arrives at \$v\$ with a price \$w\$. ...
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0answers
817 views

Depth First Search using Adjacency List

My aim to implement adjacency list correctly. After takin help from here, I have implemented it. I have tried to implement it here, but it was suggested that it is most likely adjacency matrix. Help ...
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1answer
8k views

Directed Graph Implementation in Java

Here I've attached my java implementation of a directed graph. I've used a modified adjacency-list mechanic to utilize a map instead of a list for quicker lookup times. Looking for comments / ...
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1answer
777 views

Binary Search Tree Implementation in Java

Looking for critiques on my BST implementation, particularly to check if I'm building the common operational methods and traversal algorithms properly. Code has been lightly tested, and I've tried to ...
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1answer
989 views

DFS implementation

I implemented DFS using recursion in Go. When I dfs the graph, I am able to get the path of traversal. But I'm unsure what else could I add to this DFS in order to make the search better. Also, Is ...
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Ruby Sudoku Solver without classes

I'm writing a Sudoku solver in Ruby to complete a coding challenge with the following restrictions. Failing to follow the following restrictions will result in an invalid submission: Do ...
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2answers
942 views

DFS implementation in Rust

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1answer
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I want to check neighborhoods of cell in two dimensional array in C++

I want to write a function which will return all possible/valid 'X' moves around my Target cell depending on it position inside the following two dimensional array. ...
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1answer
260 views

At least 2 paths down the binary tree have the same sum

Problem statement Write a function that given a binary tree, returns true if at least 2 paths down the tree have the same sum. A path is a series of nodes from the root to the leaf. Examples: ...
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0answers
119 views

Timeout on Python code to count connected components on HackerRank

I'm trying to solve the "Roads and Bridges" problem on HackerRank https://www.hackerrank.com/challenges/torque-and-development/problem I believe the code works, but just needs to be optimized for ...
4
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1answer
398 views

Longest Increasing Path in a Matrix from leetcode

Solved this: Given an integer matrix, find the length of the longest increasing path. From each cell, you can either move to four directions: left, right, up or down. You may NOT move ...
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0answers
347 views

BinaryTree traversed in postorder (DFS), iteratively

I was given this coding question for a technical interview: Given a binary tree, implement a method to populate the list post_ordered_list with the data of the nodes traversed in postorder, ...
5
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1answer
3k views

Sudoku solver recursive solution with clear structure

Problem statement Similar to Leetcode 37 Sudoku solver, the algorithm is to determine if the sudoku board can be filled with ‘1’,‘2’,…,‘9’. A sudoku board is represented as a two-dimensional 9x9 ...
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1answer
109 views

templated Depth-FirstSearch algorithm

I have worked on a simple iterative implementation of the common DFS algorithm for my personal template library. The algorithm itself works, but I try to get a feeling for how to seperate the data and ...
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1answer
1k views

Breadth- and Depth- First Search in C#

Another recreational implementation for review! As a side comment, for some reason I just feel like if (visited.Contains(vertex)) { .. } isn't necessary, as this ...
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599 views

Make DFS Implementation faster for 8 puzzle problem in Python

I am implementing DFS algorithm for the 8 puzzle problem which works fine if the goal is reached in less than 10 iterations. But for longer number of iterations, my implementation doesn't return the ...
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2answers
319 views

Depth-first search of a graph in C# (HackerRank problem)

I'm trying to solve a problem from HackerRank. I got the correct algorithm, but it seems to be too inefficient. After checking the code with 10 given test cases, 3 cases are good and 7 return a ...
4
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2answers
735 views

Given two words and a dictionary's word list, find all shortest transformation sequence

This is a leetcode problem (https://leetcode.com/problems/word-ladder-ii/description/) Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(...