Name: 15-Puzzle:Gem Puzzle, Boss Puzzle, Game of Fifteen
Rating: 4.9 (9 reviews)
Author: Jasonluo

数字推盘游戏（15puzzle/N-puzzle），又名数字华容道，是一种智力游戏，常见的类型有十五数字推盘游戏和八数字推盘游戏等。也有以图画代替数字的推盘游戏。

游戏介绍
可能由Noyes Palmer Chapman在1874年发明十五数字推盘，但Sam Loyd则在1891年也宣称为其发明。
八数字推盘（又名重排九宫）则可能由Henry Ernest Dudeney发明，并且Martin Gardner在科学人寻求更快的解答。
也有人认为重排九宫是传统中国游戏，来自洛书，并且为华容道的祖先。

构造
数字推盘游戏是由一块有凹槽的板和写有数字的方块所组成。
十五数字推盘游戏的板上会有十五个方块和一个大小相当于一个方块的空位（供方块移动之用）。
而八数字推盘游戏，为九宫格布局，有八个方块和一个空位。

游戏目标
让所有的方块顺着数字的次序排列。

数字华容道-数字拼图，益智游戏、15-Puzzle

The 15 puzzle (also called Gem Puzzle, Boss Puzzle, Game of Fifteen, Mystic Square and many others) is a sliding puzzle which has 15 square tiles numbered 1 to 15 in a frame that is 4 tile positions high and 4 positions wide, with one unoccupied position. Tiles in the same row or column of the open position can be moved by sliding them horizontally or vertically, respectively. The goal of the puzzle is to place the tiles in numerical order (from left to right, top to bottom).

Named after the number of tiles in the frame, the 15 puzzle may also be called a 16 puzzle, alluding to its total tile capacity. Similar names are used for different sized variants of the 15 puzzle, such as the 8 puzzle, which has 8 tiles in a 3×3 frame.

The n puzzle is a classical problem for modelling algorithms involving heuristics. Commonly used heuristics for this problem include counting the number of misplaced tiles and finding the sum of the taxicab distances between each block and its position in the goal configuration.[1] Note that both are admissible. That is, they never overestimate the number of moves left, which ensures optimality for certain search algorithms such as A*.[1]

ref: https://en.wikipedia.org/wiki/15_puzzle