Sliding Puzzle
Slide tiles to put numbers in order. 1 starts top-left, empty space goes bottom-right.
FAQ
The sliding puzzle (also called the 15-puzzle) has numbered tiles in a grid with one empty space. Slide tiles to arrange them in numerical order. It was invented in 1874 and became a worldwide craze.
Exactly half of all possible arrangements are solvable. The puzzle's solvability depends on the number of inversions (pairs out of order). If the starting position has an even number of inversions, it is solvable.
For the classic 15-puzzle (4x4), the maximum minimum solution requires 80 moves. Most random solvable positions can be solved in 50-60 moves by experienced solvers.
About this test
The sliding puzzle is a classic brain teaser that has challenged minds since 1874. Arrange the numbered tiles in order by sliding them through the empty space.
How It Works
Tiles can only move into the empty space by sliding horizontally or vertically. Rearrange all tiles into numerical order. The fewer moves you use, the better.
History
The 15-puzzle caused a worldwide craze in the 1880s when a $1,000 prize was offered for solving an unsolvable configuration. The prize was never claimed — mathematically, half of all arrangements cannot be solved.
Tips
- Solve the top row first, then the second row
- Work on the left column of the remaining grid
- Use the 3-tile rotation technique for the final 2x3 section