N-Queens Visualizer — Backtracking
Animated N-Queens backtracking on a chessboard — try, place, conflict, and backtrack with step controls. Runs in your browser.
Pseudocode
Press Run to animate the algorithm.
Time · Space
How to use
- 1 Press Run to place queens column by column with backtracking.
- 2 A blue cell is being tried; a red cell conflicts with an existing queen.
- 3 When a column has no safe row, the search backtracks to the previous column.
- 4 Use Shuffle for a different board size, or step through the search.
Why use this tool
- See backtracking explore, hit dead ends, and undo its choices.
- Understand the safety test: no two queens share a row, column, or diagonal.
- A canonical constraint-satisfaction and backtracking example.
- Runs entirely in your browser. No signup, no uploads.
Frequently asked questions
What is the N-Queens problem?
Place n queens on an n×n chessboard so that no two attack each other — no shared row, column, or diagonal.
How does backtracking solve it?
Place queens one column at a time. For each column try each row; if it is safe, recurse to the next column; if no row is safe, backtrack and try a different row in the previous column.
What is the time complexity?
Worst case is roughly O(n!), but pruning conflicting placements makes finding a single solution far faster in practice.
For which n does a solution exist?
Solutions exist for every n except 2 and 3. The classic 8-queens puzzle has 92 distinct solutions.
What is N-Queens Visualizer?
An N-Queens Visualizer animates backtracking search placing n queens on an n×n board so none attack each other. It tries each row of a column, marks conflicts, recurses when a placement is safe, and backtracks when a column has no safe row.
N-Queens Visualizer is a free algorithm utility by Zerethon Tools. Animated N-Queens backtracking on a chessboard — try, place, conflict, and backtrack with step controls. Runs in your browser. Runs entirely in the browser — no signup, no upload.
- Category
- Algorithm
- Pricing
- Free
- Privacy
- Browser-based
- Signup
- Not required
Privacy
Your data never leaves your browser unless explicitly stated. N-Queens Visualizer runs entirely client-side — no server upload, no logging, no tracking of your input.
New to this? Read the step-by-step explanation with Big-O analysis: Learn Dynamic Programming →
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