Animated side-by-side visualisation of two algorithms racing to solve the N-Queens problem — watch blind depth-first search and A* heuristic search compete in real time.
Place N queens on an N×N chessboard so that no two share a row, column, or diagonal. The classic 8-queens puzzle has 92 distinct solutions.
Two fundamentally different strategies attack the same problem simultaneously:
Blind Search (Depth-First) places queens column by column, trying each row in order. When a conflict is detected it backtracks to the previous column and increments the row. No domain knowledge is used — it explores the space exhaustively. For N=8 this takes 764 attempts.
Heuristic Search (A*) starts from a randomly seeded board with all queens already placed. Each iteration picks the board state with the fewest conflicting pairs and expands it by trying every possible single-queen move. The heuristic guides the search toward valid configurations — N=8 needs only 47 attempts.
The contrast is the whole point: watching both boards animate in parallel makes the efficiency gap immediately visible.
This started as Assignment 1 for COSC 3P71 — Introduction to Artificial Intelligence at Brock University, submitted in October 2017. The original implementation is preserved verbatim as a historical baseline — the algorithm logic in NQueens.java and Board.java is unchanged from the 2017 submission.
- Java 21+
- Maven 3.6+
git clone https://github.com/GrahlmanMatthew/N-Queens-Problem.git
cd N-Queens-ProblemRun the visualisation:
mvn javafx:runThe app opens with two animated boards. Use the controls at the bottom to:
- Set N (board size, 4–20)
- Adjust animation speed
- Start or reset the race
Run the original CLI solver (outputs to output.txt):
mvn compile exec:java -Dexec.mainClass="nqueens.NQueens"mvn test