Here are some basic first steps:

1. find a data structure that represents the 15-puzzle. This could be a 4x4 matrix, for example. At the beginning, 15 cells are given a value and

the free field could be defined as 0. A flexible data structure in C++ for the data field, which also makes it acceptable to change the dimension, would be a vector. It could look something like this:

C++

// Data of the puzzle field class PuzzleGrid { public: // constructor that determines the size of the puzzle PuzzleGrid(int rows, int cols) : grid(rows, std::vector<int>(cols, 0)) {} void setValue(int row, int col, int value) { grid[row][col] = value; } int getValue(int row, int col) const { return grid[row][col]; } private: std::vector<std::vector<int>> grid; // The puzzle field }; struct Point { Point(int x, int y): x(x), y(y) {} // Constructor int x, y; // X,y position }; // State of the puzzle struct PuzzleState { // constructor PuzzleState(const PuzzleGrid& data, const Point& emptyPos): puzzleData(data), emptyCellPos(emptyPos) {} // States PuzzleGrid puzzleData; // The assignment of the playing field Point emptyCellPos; // The position of the empty field };2. write an initial test program that uses the data structure. You would also need a function to display the field on the screen, as well as a function that shuffles the field. Functions are also needed to move the empty field in all directions (up, down, left, right), if possible.The border must of course be taken into account when moving.

3. a function is needed that can evaluate the current state of a field. Here you could use the distance as the sum of the horizontal and vertical distances of each puzzle piece from its final position.

4. after calculating the distances of each piece to the target position, you need to use the A* algorithm to find the optimal solution path.

Set up a workable framework up to this point and think about the implementation of the A*. If further questions arise, it is best to open a new question.

Step 1:Work out what your requirements are.Step 2:Learn about the algorithm, and decide whether it is appropriate for the problem you are trying to solve.Step 3:Write some code.Nobody here is going to do your homework for you. If you genuinely don't know where to start, then talk to your teacher.