Description
The 8-puzzle problem is played on a 3-by-3 grid with 8 square tiles labeled 1 through 8 and a
blank tile. Your goal is to rearrange the blocks so that they are in order. You are permitted
to slide blocks horizontally or vertically into the blank tile. For example, consider the given
sequence:
Write a program to solve the 8-puzzle problem using each of the following algorithms:
1. Breadth-first search (10 points)
2. Iterative deepening search (10 points)
3. A* search using two different suitable heuristics (15 points)
5 points for analysis section described on the next page.
Please note that you must implement all the algorithms and not use any implementation
provided by another library or package. Your program should read the initial board configuration from the standard input and print to the standard output a sequence of board
positions that solves the puzzle (only the path to goal from start), the total number of
moves and the total number of search states enqueued. For each of the above algorithms,
expand the search only until depth 10, root being at depth 0. If goal state is not reached
before or at depth 10, then return a failure message. Example, consider the given input and
corresponding output sequence.
Input (Any random position of the tiles):
* 1 3
4 2 5
7 8 6
Output (List of states starting from input to goal state, if found):
* 1 3 (Initial input state)
1
4 2 5
7 8 6
1 * 3
4 2 5
7 8 6
1 2 3
4 * 5
7 8 6
1 2 3
4 5 *
7 8 6
1 2 3 (Goal state)
4 5 6
7 8 *
Number of moves = 4
Number of states enqueued = 10
Note: * represents an empty tile
What to turn in: Your code and a readme file for compiling the code in a ‘.zip’ file. Kindly
ensure that only these two files are present in the zip file. The readme file should contain
the following things:
1. Instructions on how to run the program
2. Sample input and its corresponding output
3. Provide a short comparative analysis of two heuristics used for A* (5 points)
You may use any of the following languages for your program: Python, Java, C, C++. Please
make sure your program runs in the following way:
Python example: python homework1.py
where:
algorithm_name can take one of the following values:
– bfs : For running the Breadth-first search algorithm
– ids : For running the Iterative deepening search algorithm
– astar1 : For running the A* algorithm with heuristic 1.
– astar2 : For running the A* algorithm with heuristic 2.
space_separated_input is the input sequence for the 8-puzzle problem.
Example: * 1 3 4 2 5 7 8 6
2
Output of the program: Sequence of board positions that solves the problem, total number
of moves and total number of states enqueued OR A failure message if goal state was not
found before or at depth 10.
3
