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Rui Ribeiro f1b9d38007 Edited `README`'s, added `broken_gnl` exercise, `LICENSE` and main `README`		2025-10-05 17:10:55 +01:00
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Makefile	added level-1	2025-09-23 08:41:21 +01:00
n_queens_clean.c	Added cleaner resolution for level-2 n_queens	2025-09-29 22:28:33 +01:00
n_queens.c	Replaced subject resolutions of level-2 with backtracking	2025-09-25 08:16:02 +01:00
README.md	Edited `README`'s, added `broken_gnl` exercise, `LICENSE` and main `README`	2025-10-05 17:10:55 +01:00
subject.txt	added level-1	2025-09-23 08:41:21 +01:00

README.md

N-Queens

What is the N-Queens Problem?

Imagine you have a chessboard and some queens (the most powerful pieces in chess). The N-Queens problem is like a puzzle where you need to place N queens on an N×N chessboard so that none of them can attack each other.

What's a Queen in Chess?

A queen is the strongest piece in chess. She can move:

Horizontally (left and right)
Vertically (up and down)
Diagonally (in any diagonal direction)

She can move as many squares as she wants in these directions!

The Challenge

Let's say we want to solve the 4-Queens problem (N=4):

We have a 4×4 chessboard (16 squares total)
We need to place 4 queens
NO queen can attack any other queen

Example: What Does "Attack" Mean?

If we put a queen at position (0,0) - that's the top-left corner - she can attack:

Q . . .  ← Queen here attacks all positions marked with X
X . . .
X . . .
X . . .

Q X X X  ← Queen attacks horizontally
. . . .
. . . .
. . . .

Q . . .  ← Queen attacks diagonally
. X . .
. . X .
. . . X

So we can't put any other queen in any of those X positions!