N-Queens vs. Queens Puzzle: What's the Difference?

If you've studied computer science, you've probably met the N-Queens problem: place N chess queens on an N×N board so that no two attack each other. The Queens puzzle (the one that went viral through LinkedIn's daily game) looks like the same idea at first glance, but it adds one rule that changes the entire solving process - colored regions.

The Classic N-Queens Problem

In N-Queens, the only constraints are rows, columns, and diagonals - a queen attacks along all three. The classic 8-queens problem has 92 distinct solutions, and the puzzle is famous in computer science as a benchmark for backtracking algorithms: try a placement, recurse, and backtrack when a later row has no legal column left. There's no single 'correct' solution - any of the 92 arrangements is valid.

The Queens Puzzle's Twist: Colored Regions

The Queens puzzle keeps the row, column, and diagonal-adjacency rules, but adds a new constraint: the board is divided into colored regions, and each region must contain exactly one queen too. This one addition has two big effects. First, it collapses the puzzle from 'many valid solutions' to exactly one - the regions are hand-designed so that only a single arrangement satisfies every constraint simultaneously. Second, it changes how you solve it: instead of a search-and-backtrack algorithm, human solvers use elimination logic, because the regions create forcing chains that N-Queens simply doesn't have.

Why This Makes It a Different Kind of Puzzle

• N-Queens is a constraint-satisfaction search problem - great for teaching algorithms, but any of many solutions is 'correct.'
• The Queens puzzle is a deductive logic puzzle, closer in spirit to Sudoku - a unique solution exists, and it's reachable through step-by-step elimination without guessing.
• Region shapes in the Queens puzzle are designed by hand (or by a generator tuned for difficulty), the same way Sudoku puzzles are designed with a target difficulty in mind - unlike N-Queens, where any N produces the same type of problem regardless of 'difficulty.'
• Diagonal adjacency in the Queens puzzle only blocks the 8 immediately surrounding cells, not the full diagonal line the way a chess queen attacks in N-Queens.

Which One Should You Play?

If you want to explore backtracking algorithms or classic CS theory, N-Queens is the right reference problem. If you want a daily logic puzzle with a satisfying, unique solution - the same appeal as Sudoku or a crossword - the Queens puzzle is built for exactly that.