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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Recursive Backtracking in c++

I am trying to write a program that will use backtracking to create a Sudoku solver. I have been able to create a black Sudoku grid and I can check to see if a move is a valid move. My program works fine until there are more than one choice of…
Asuu
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How to calculate time complexity for a backtracking algorithm

Details of the question and algorithm Given a MxN grid, how many paths can there be to reach the bottom right cell from the top left cell? On any grid, you can move in four directions. The only constraint is that one cannot visit a cell more than…
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what is the algorithm behind the solution below

I encountered recursive exercises for improving my coding skills and found the following problem. Given an array of ints, is it possible to choose a group of some of the ints, such that the group sums to the given target? Rather than looking at the…
mehmet riza oz
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Converting string containing multidimensional array keys and values PHP

I use TPP API for check domain availability and domain register but i receive response in string. Get Session, return stringOK: t73484678463765 Domain check, return string woohoo123.nz: OK: Minimum=1&Maximum=2 In other case, return string…
Ian Patel
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how to make undo in backtracking? I'm having problems with the recursively backtracking method

Well, I have this graph: I have to make a code based in Branch and Bound and using backtracking, that has to show the optimum way to match the nodes of a graph. So in this example, the optimum solution must be >> [(1,4),(2,3)]. But my algorithm,…
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Too many solutions to coin change maker

The objective of my program is to output all possible change solutions to a given amount of money, for example DESIRED OUTPUT Change: 9 [1, 1, 1, 1, 5] [1, 1, 1, 1, 1, 1, 1, 1, 1] (with 9 = $0.09) However my output is a little different, my output…
Junikin
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What's time complexity of this Algorithm for breaking words? (Dynamic Programming)

Word Break(with Dynamic Programming: Top->Down) Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences. For example, given s =…
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Finding path in Maze

I recently gave an interview and was asked the following question. A maze is a group of linked Places. Each Place has a North, South, East, and West Place adjacent to it. There are two special pre-defined Place's: Place Wall represents a wall -…
XConfusion
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Knights tour backtracking lasts too long

How long does it last to solve the knights tour problem with backtracking on an 8x8 board? Because my algorithm already computes somehow too long and it seems, like it wont finish. But when I try a 6x6, or 5x5 board, it finishes successfully. the…
user2208931
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How are recursive backtracking returns handled with the void type

To generalize this question I am borrowing material from a Zelenski CS class handout. And, it is relevant to my specific question since I took the class from a different instructor several years ago and learned this approach to C++. The handout is…
forest.peterson
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write a program in java to return the list of the subsets of a given array with the help of backtracking and recursion without using loops

import java.util.ArrayList;` public class Main{ public static void main(String[] args) { ArrayList nums = new ArrayList<>(); List> list= new ArrayList<>(); int[] arr = {2,3,5}; …
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Leetcode 1601. Maximum Number of Achievable Transfer Requests

I am trying to solve LeetCode problem 1601. Maximum Number of Achievable Transfer Requests : We have n buildings numbered from 0 to n - 1. Each building has a number of employees. It's transfer season, and some employees want to change the building…
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Recursive approach with and without manual backtracking

In some cases, like the "hasPathSum" problem, where we are checking for a specific condition (e.g., targetSum == 0) at leaf nodes, we don't need manual backtracking. The recursion naturally backtracks as it reaches the leaf nodes, and the state is…
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Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order?

I am working on LeetCode problem 46. Permutations: Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. I thought to solve this using backtracking. My idea is to image this problem…
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Not able to save the current state of variables in the global array in nested functions in Python (Very confusing title, please read description)

I have made this python program to solve a sudoku and save all its possible valid answers in an array and return it. But it is failing in doing so. The logic is perfect and is being executed perfectly. But the problem is that that in both the nested…