If the index is at the end of the matrix, i.e. Create a recursive function that takes a grid and the current row and column index.If any number has a frequency greater than 1 in the hashMap return false else return true Keep Hashmap for the row, column and boxes. Create a function that checks if the given matrix is valid sudoku or not.If safe print else recurs for other cases. After filling all the unassigned position check if the matrix is safe or not. for every unassigned position fill the position with a number from 1 to 9. Try every configuration one by one until the correct configuration is found, i.e. The output matrix contains unique numbers.Īpproach: The naive approach is to generate all possible configurations of numbers from 1 to 9 to fill the empty cells. Top 20 Backtracking Algorithm Interview QuestionsĮxplanation: Each row, column and 3*3 box of.Fill two instances of all numbers from 1 to n in a specific way.Match a pattern and String without using regular expressions.Longest Possible Route in a Matrix with Hurdles.Partition of a set into K subsets with equal sum.Minimize number of unique characters in string.Fill 8 numbers in grid with given conditions.Count all possible paths between two vertices.Find shortest safe route in a path with landmines.Print all longest common sub-sequences in lexicographical order.Print all possible strings that can be made by placing spaces.Printing all solutions in N-Queen Problem.Warnsdorff’s algorithm for Knight’s tour problem.Print all possible paths from top left to bottom right of a mXn matrix.

Rat in a Maze with multiple steps or jump allowed.Write a program to print all permutations of a given string.Solving Cryptarithmetic Puzzles | Backtracking-8.The Knight’s tour problem | Backtracking-1.ISRO CS Syllabus for Scientist/Engineer Exam.ISRO CS Original Papers and Official Keys.GATE CS Original Papers and Official Keys.

Sudoku origin