Top 20 Backtracking Algorithm Interview Questions

Backtracking is a powerful algorithmic technique used to solve problems by exploring all possible solutions in a systematic and recursive manner. It is particularly useful for problems that require searching through a vast solution space, such as combinatorial problems, constraint satisfaction problems, and optimization tasks.

In backtracking, we build solutions incrementally, making safe choices at each step. If a choice leads to a dead end (invalid solution), we backtrack to the previous step and try a different path. This method ensures that we efficiently navigate the solution space while avoiding unnecessary computations.

Easy Problems

1. Rat in a Maze
2. Print all permutations of a given string
3. Print palindromic partitions string
4. Print all possible paths from top left to bottom right of a mXn matrix
5. Subset sum
6. Tug of war

Medium Problems

1. N Queens Problem
2. Word Break Problem
3. Find Path from corner cell to middle cell in a maze
4. Hamiltonian cycle
5. Sudoku
6. M Coloring Problem
7. Cryptarithmetic puzzle
8. Find if there is a path of more than k length from a source
9. Partition of a set into k subsets with equal sum

Hard Problems

1. Warnsdorff's Algorithm
2. Remove Invalid Parenthesis
3. Match a pattern and string using regular expression
4. longest possible route in a matrix with hurdles
5. Shortest safe route in a path with landmines

Further Practice: Coding Practice on Backtracking