The N-Queens Problem
Goal: Place N queens on an N × N chessboard so that no two queens threaten each other.
Queens can attack horizontally, vertically, and diagonally, so none can share a row, column, or diagonal.
Example:
N = 4 → there are 2 solutions.
N = 8 → the famous "8-Queens problem" has 92 solutions.
Computer Demo
A computer demo typically shows:
Board Setup
An empty chessboard appears on the screen.
The program tries to place queens one by one.
Backtracking in Action
The algorithm places a queen in the first safe spot of a row.
If a conflict arises later, it backtracks (removes the queen and tries the next spot).
This continues until all N queens are safely placed.
Visualization
Each step can be shown live:
Queens appearing/disappearing.
Conflicted squares marked with red highlights.
Valid placements shown with green queens.
Once a solution is found, the full board is displayed.
Multiple Solutions
For larger N, the demo can cycle through all valid solutions automatically.
Sometimes, animations show symmetry between solutions.
Educational Value
Demonstrates recursion and backtracking.
Makes abstract algorithms visual and interactive.
Can be scaled: N = 4 (small puzzle) up to N = 20 or more (big challenge).