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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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6 votes
3 answers
692 views

Program that brute forces to find the minimum dominating set

This program solves the minimum dominating set but it takes an insanely long time to run. In case you do not know, in graph theory, a dominating set for a graph G is a subset D of its vertices, such ...
BeginnerProgrammer6's user avatar
2 votes
1 answer
254 views

Finding the longest path on a grid with obstacles from the top to the bottom

I have a rectangle of . (platforms) and # (obstacles). I can start at any platform in the top row and go to the left, right or ...
Aliaksei Badnarchuk's user avatar
1 vote
1 answer
114 views

Order of values in dfs and bfs

Let's consider a matrix of integers m: [[1,2,3] [4,5,6] [7,8,9]] Which represents a graph: ...
Gameplay's user avatar
  • 161
1 vote
0 answers
178 views

Backtracking graph algorithms for a word puzzle in Python

Motivation Recently, Buzzfeed released a browser-based puzzle game called "Pyramid Scheme." It is available at the following link. The puzzle in an initial state looks like this: To solve ...
WilliamMorris's user avatar
3 votes
1 answer
69 views

Optimize Island Counter program

I am doing some assignments on my own and one of them is about a Island Counting program, I have come up with a working program but the problem is its very slow. When running test on for example maps ...
phuck's user avatar
  • 33
1 vote
0 answers
110 views

USACO Silver "Wormhole Sort" solver

I'm struggling a bit with a USACO silver question using python, http://usaco.org/index.php?page=viewproblem2&cpid=992. The question provides an unsorted list of numbers (cows) and a number of ...
Luke's user avatar
  • 11
3 votes
1 answer
130 views

Exceeded time limit on Trie search with Backtracking using Swift

I have been trying to solve Trie related problems over at leet code and came across this interesting problem 211. Design Add and Search Words Data Structure Here is the question for convenience: 211. ...
Shawn Frank's user avatar
1 vote
1 answer
68 views

Shortest path in dags: Part 2/3 - the preprocessing and shortest path algorithms

Part 1/3 Part 3/3 I have this library for performing shortest path queries on dags (directed acyclic graphs). This post presents the shortest path algorithms and the topological sorters. Two ...
coderodde's user avatar
  • 28.4k
1 vote
3 answers
90 views

DFS search that returns "not found" or distance

Assuming I've the following code: ...
Regyn's user avatar
  • 143
0 votes
1 answer
235 views

Find the shortest path from bottom left to top right in a maze using dfs and bfs algorithm

The following code is applying the depth-first search and breadth-first search algorithm to find the shortest path from bottom left to top right in a 10 x 10 grid. ...
Mohamed Magdy's user avatar
0 votes
1 answer
169 views

Recursive DFS to find Euler Cycle

I have referred to this for what constitutes as an Euler Cycle: https://xlinux.nist.gov/dads/HTML/eulercycle.html This assignment required me to use Depth First Search and have the methods I have ...
William Golovlev's user avatar
1 vote
1 answer
948 views

Helper get_all_neighbors (in a grid) function - python

So a little context to understand the code: This is a helper function to solve a bigger problem here Quick summary: A Knight is in a dungeon/2D grid of Ints, starts at 0,0 and must reach the last ...
Sergio Bost's user avatar
1 vote
0 answers
354 views

Codewars: Path Finder

Task 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). Return true if you can reach position [N-1, N-1] or false ...
Михаил Спирин's user avatar
1 vote
1 answer
76 views

Loan graph simplification in Java: the recursive DFS for searching for directed cycles

The class in this post returns a directed cycle in a financial loan graph. A financial loan graph consists of nodes and directed arcs. If there is an arc \$(u, v)\$ with weight \$w = w(u, v)\$, then ...
coderodde's user avatar
  • 28.4k
0 votes
1 answer
1k views

Find Passable Lanes in Rows and Columns

I have implemented the following question and looking forward for the reviews. Question Explanation : We have a two-dimensional board game involving snakes. The board has two types of squares on it: +...
Neslihan Bozer's user avatar
0 votes
2 answers
190 views

Given a 2d matrix with chars find the target string

I am looking for a simpler implementation of the following question. Could it get better? I am expecting the new solution via DFS again. Thanks. OA: Given a 2d matrix with chars and a target string. ...
Neslihan Bozer's user avatar
1 vote
1 answer
1k views

How does one write DFS in python with a Deque without reversed for Trees?

I have implemented a correct version of DFS (with comments explaining the implementation): ...
Charlie Parker's user avatar
3 votes
2 answers
387 views

Check if point is inside a bitmap shape

Inspired by this question, here's some C code to check if a point is "inside" of a shape on a simple black and white bitmap. For this exercise: Set bits form the "outlines" of a ...
user673679's user avatar
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7 votes
6 answers
4k views

C++ implementation of depth-first search

I got the C++ implementation of depth-first search (DFS) from here and made slight modifications to it. The modified code is as follows: ...
a_sid's user avatar
  • 425
1 vote
0 answers
104 views

Improving speed of parsing XML file

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adb12's user avatar
  • 11
3 votes
1 answer
414 views

Detecting a cycle in a directed graph via an adjacency list implementation and a recursive DFS

Here's my attempt. I iterate through each vertex in the graph and do a DFS to see if I reach back on a vertex I already visited in this vertex's iteration. It seems to work but I am not satisfied with ...
user2495123's user avatar
2 votes
0 answers
72 views

LeetCode: Number of enclaves C#

https://leetcode.com/problems/number-of-enclaves/ Given a 2D array A, each cell is 0 (representing sea) or 1 (representing land) A move consists of walking from one land square 4-directionally to ...
Gilad's user avatar
  • 5,311
6 votes
1 answer
275 views

Graph: Depth First Search (N citizens with pairs of friends)

I have solved problem 10608 on UVA Online Judge using Python 3.5.1. My solution works, but it takes too long to run when the online judge evaluates it. Problem There is a town with N citizens. It is ...
Kyssmark's user avatar
5 votes
1 answer
689 views

01 Matrix is too slow when solved using DFS

I tried solving Leetcode 01 Matrix problem. It is running too slow when solved using DFS approach. Given a matrix consists of 0 and 1, find the distance of the nearest 0 for each cell. The distance ...
Akanksha's user avatar
  • 129
6 votes
2 answers
17k views

Depth First Search Using Stack in Python

I have implemented a depth first search using a stack (in a separate class). Any suggestions please on improvements for the below code: ...
Saurabh's user avatar
  • 435
5 votes
1 answer
123 views

Closest Pair heuristics, graph with adjacency matrix in C++17

I was trying to solve a problem that was briefly mentioned at the beginning of the "The Algorithm Design Manual" by Steven Skiena (Ch 1, Problem 26). It took me some time to build a working ...
Mikhail Kalashnikov's user avatar
4 votes
1 answer
347 views

LeetCode 839: Similar String Groups II

I'm posting my code for a LeetCode problem. If you'd like to review, please do so. Thank you for your time! Problem Two strings X and Y are similar if we can swap two letters (in different positions) ...
Emma's user avatar
  • 3,527
4 votes
1 answer
291 views

Sudoku solver using backtracting and depth-first-search

I've recently finished my first ever C program. I implemented a Sudoku solver that uses backtracking. Does my code look like a proper C-program? Are there any recommendations for improving my code? <...
Ivan Shelomentsev's user avatar
2 votes
1 answer
370 views

Sum of all Paths in Binary Tree

Problem For the given binary tree return the list which has sum of every paths in a tree. i.e Every path from root to leaf. I've written following solution. ...
Ashish Pawar's user avatar
1 vote
0 answers
371 views

Kosaraju Algorithm in Java

Problem statement In simple words it say, count total Strongly connected components in the graph. All edges are undirected. I have the following code that uses ...
Ashish Pawar's user avatar
8 votes
1 answer
1k views

Recursive and iterative implementation on Kosaraju algorithm

Kosaraju algorithm is mainly phrased as two recursive subroutines running postorder DFS twice to mark SCCs with linear time complexity O(V+E) below, For each vertex \$u\$ of the graph, mark \$u\$ as ...
sof's user avatar
  • 181
1 vote
1 answer
81 views

Depth First Search vs Breadth First Search

So after years of teaching myself, I think I'm ready to stand on the shoulders of giants and ask you a good question! I have a tree of nodes. What I want is a function that returns an array of the ...
aName's user avatar
  • 143
1 vote
0 answers
327 views

GeeksForGeeks: Alien dictionary C#

https://www.geeksforgeeks.org/given-sorted-dictionary-find-precedence-characters/ please review for performance, the adjacency list is the problematic part for me. Given a sorted dictionary (array ...
Gilad's user avatar
  • 5,311
1 vote
0 answers
299 views

LeetCode:MineSweeper C#

https://leetcode.com/problems/minesweeper/ please review for performance. I really don't like the implementation I made for GetNumberOfMines() function, but within the time limits i did this. it is ...
Gilad's user avatar
  • 5,311
1 vote
1 answer
218 views

LeetCode: FloodFill C#

https://leetcode.com/problems/flood-fill/ An image is represented by a 2-D array of integers, each integer representing the pixel value of the image (from 0 to 65535). Given a coordinate (sr,...
Gilad's user avatar
  • 5,311
3 votes
0 answers
174 views

N-Queens Puzzle

The N-Queens puzzle can be solved in many ways. One is by a depth-first-search backtracking algorithm. Below is my generalized version using mutual recursion: ...
user avatar
1 vote
0 answers
293 views

LeetCode: Network Delay Time DFS solution C#

https://leetcode.com/problems/network-delay-time/ There are N network nodes, labelled 1 to N. Given times, a list of travel times as directed edges times[i] = (u, v, w), where u is the ...
Gilad's user avatar
  • 5,311
-1 votes
2 answers
78 views

algorithm to find a zero in a board game [closed]

I got asked this question in an interview and I came up with a solution which I shared in the below but apparently it was not enough to pass. I'm looking forward to hearing how this problem could be ...
Ugur Yilmaz's user avatar
6 votes
1 answer
266 views

Clojure depth first search maze problem from Classic CS Problems in Python Book

I am an experienced self-taught professional Python programmer working my way through the book Classic Computer Science Problems in Python to try to catch myself up on some of the things I missed by ...
user5293's user avatar
  • 163
3 votes
1 answer
121 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. ...
Kerry Huang's user avatar
5 votes
0 answers
216 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 ...
Evgeny Zislis's user avatar
3 votes
1 answer
75 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 ...
Clock Slave's user avatar
1 vote
0 answers
1k 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-...
Gilad's user avatar
  • 5,311
5 votes
2 answers
456 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 ...
Hoang Hai's user avatar
3 votes
1 answer
2k 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). ...
Ender Look's user avatar
3 votes
1 answer
51 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 ...
Alex F's user avatar
  • 443
4 votes
2 answers
1k 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 ...
Alex F's user avatar
  • 443
2 votes
2 answers
258 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 ...
user3769323's user avatar
2 votes
1 answer
392 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 <...
justanothertechdude's user avatar
1 vote
0 answers
300 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 squares ...
nz_21's user avatar
  • 1,041