DSA Lab
Backtracking: N-Queens
Backtracking builds a solution one choice at a time and undoes the last choice as soon as it cannot lead anywhere. For N-Queens, each choice is a column for the queen in the next row.
Backtracking: N-Queens: how it works
In this tool: try, check, undo. Put in your own values and watch it change. Each operation runs one step at a time and says in plain words what happened, with its calculation worked out. The code is shown in Python, C, C++ or Java with the line that just ran marked, and an Understand it panel gives the idea, why it works, the cost of each operation, common mistakes and a short quiz.
Lessons that use it
- Recursion and backtracking (Algorithms)Try every choice, undo it, try the next: all subsets, all permutations, and placing queens that never attack.
- Backtracking (Interview Prep)Build every solution one choice at a time and undo each choice afterwards: subsets, permutations, combination sum, and pruning branches that cannot succeed.