Questions tagged [recursive-backtracking]

Recursive backtracking is a general algorithm for finding solutions to computational problems that incrementally builds partial solutions and drops those which are identified as futile *as early as possible*.

Recursive backtracking is a general algorithm for finding solutions to computational problems that incrementally builds partial solutions and drops as early as possible those partial solutions which are identified as futile i.e. such that can not lead to a correct solution.

It essentially involves building nested loops through recursion. Each loop embodies a series of choices. Each inner loop can accept a partial-solution-so-far and try its own choices in a loop, or reject the partial solution it is presented with, through early exit or an equivalent of the continue or break etc. statement.

The control is inverted in that the full solution is achieved in the innermost loop, which can act on it in a particular manner, like printing it to the output / external file, or calling a callback with the solution as an argument.

The backtracking computational structure is embodied in the states of the nested loops, in each of the nested loops' loop variables.

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Backtracking in a recursive maze; python

I'm coding a maze solving algorithm and I'm having trouble with the backtracking once you hit a "wall" So far I have that my code checks some basic recursive cases such as if I've reached the end or if I have checked all points. I've also made it so…
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Python Recurisve Backtracking to create a maze

I'm trying to create a maze through recursive backtracking but I can't seem to call create_maze() properly. From my main menu I call the maze class like this maze = Maze.create_maze(NoOfRows, NoOfColumns) However, I get an argument error from…
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Implementing a recursive backtracker to generate a maze

I'm trying to make a recursive create maze function, however, I am stuck as I do not know how to recursively call it and place the walls. Can someone tell me how to edit my code to make it work? Thanks EDIT: Since I didn't add my maze class in, I…
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What does array[:] exactly do in this backtracking algorithm, or rather in Python?

So, I was solving(or rather, looking at the solution haha) a question on Leetcode, and this was a solution to allow you to generate all possible permutations of an array with unique integers. class Solution: def permute(self, nums: List[int]) ->…
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How do you compute for time complexity for Backtracking - Traveling salesman problem?

I'm having trouble finding the time complexity for Backtracking - Traveling Salesman problem. I tried to search for Hamiltonian cycle's time complexity since Backtracking - Traveling Salesman problem uses it and these are what i found: I've seen…
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Javascript Recursive Backtracking Sudoku Solver

I recently wrote this same code in Golang with some help from here. If you are familiar with go you can see the working code here. Go Playground Here is what I am trying to accomplish in python. Computerphile Video I am now trying to port this to…
user3196284
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Forming a circle/chain from set of string pairs C++

So, I have an assignment to do in C++, but I can't figure out how to :/ I have to use backtracking, which is completely alien to me. The problem: You are given n number of people with their names and m number of relations(friends) between them. Each…
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C++ Sudoku Solver using recursion backtracking not working

I'm trying to code a sudoku solver with recursion and backtracking. But my code always returns false. The SudokuSolver() traverses only the first row up to fourth column and then it stops and starts backtracking. The problem is that the backtracking…
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Why does the following code returns wrong value of count?

Problem: Given a 2D matrix of n x m. The matrix contained integers. Given a destination position, find the number of ways in which that person can reach the destination from source(origin) fulfilling the following conditions- (i) Movement can be…
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How do I find the solution of a particular maze using recursive bactracking (Java)?

I am trying to write a program that solves a maze recursively. When a step has been made, an 'x' character is placed at that position in the maze and the maze is printed, if the maze reaches a dead end it backtracks its last recursive step by…
jacobay43
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How to change this backtracking code into a dynamic programming code by using memoization?

I'm trying to learn dynamic programming and hence I'm trying to solve UVA 11450. Since I know I could solve this question using backtracking, I decided to solve it using backtracking and then add memoization to the code. However, I'm unable to do…
Evil_Transistor
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How does method call work as a condition ? For recursive backtracking in Java

My question is about how exactly do method call work as a condition of an if/else statement ? I understand recursion is a method that calls itself by changing the value of its arguments, a solution is tried and if it is the right one the recursion…
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understanding constraint satisfaction problem: map coloring algorithm

I am trying to implement this recursive-backtracking function for a constraint satisfaction problem from the given algorithm: function BACKTRACKING-SEARCH(csp) returns solution/failure return RECURSIVE-BACKTRACKING({},csp) function…
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Explaining Python Example Code for Backtracking Algorithm

From the PacktPub's book "Python Data Structures and Algorithms" (authored by Benjamin Baka) section on Backtracking from chapter 3, they have this function (page 81): def bitStr(n, s): if n == 1: return s return [digit + bits for digit in…
J Doe
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Problems in code to Print the possibilities of wins in a Coin game

I am solving the below problem using backtracking recursion. The first code "CoinGame1" is providing correct solution but the second code "CoinGame2" is providing a wrong solution. I guess, there is something bad happening since i am reversing the…