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Intermediate Topic 30 of 51 Algorithms

N-Queens Problem

Placing queens on a board so none attack each other.

How it works

Place N queens on an N×N board with no two sharing a row, column or diagonal. Backtracking places one queen per row and prunes conflicts using sets for columns and diagonals.

Where it is used

Classic example of constraint satisfaction.

Common pitfall

The number of solutions grows quickly (92 for N=8); naive checking of all placements is infeasible.

Where it fits in the course

N-Queens Problem is topic 30 of 51 in Algorithms, rated Intermediate. It follows Backtracking. The next topic is Breadth-First Search.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Algorithms quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is N-Queens Problem?
Placing queens on a board so none attack each other. It belongs to Algorithms and is an intermediate-level topic.
Where do people use N-Queens Problem?
Classic example of constraint satisfaction.
What is the most common mistake with N-Queens Problem?
The number of solutions grows quickly (92 for N=8); naive checking of all placements is infeasible.
What should I learn before this topic?
Start with Backtracking, the topic just before it in Algorithms.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Algorithms quiz.
Is N-Queens Problem hard to learn?
It is an Intermediate topic. Be comfortable with the Beginner topics in this area first, then read the common pitfall carefully, since it is where most mistakes happen.
How long does it take to learn N-Queens Problem?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to N-Queens Problem?
Backtracking, Breadth-First Search, Edit Distance are closely connected. The full list is in the related topics section of this page.
What should I study after N-Queens Problem?
Continue with Breadth-First Search, the next topic in Algorithms.

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