Hello, and welcome back to our coding lesson series. In this unit, we have a fascinating problem at hand that uses the concept of 2D arrays or grids. What's interesting about this problem is that it involves not only the simple traversal of the grid but also making this traversal in a unique manner. Initially, the concept might seem a bit tricky, but as we dissect the task and take it step by step, you're sure to enjoy how it unfolds. Are you ready to embark on this adventure? Let's dive right in!
The task before us involves the creation of a Python function named path_traverse. This function should perform a particularly ordered traversal through a 2D grid. The function will accept a grid, along with the starting cell coordinates, as parameters. Starting from the provided cell, the function should make moves in any one of the four possible directions toward an adjacent cell. However, a conditions govern this selection: the new cell value should be strictly greater than the current cell's value.
This pattern would continue as we keep selecting the next available, larger cell value. The traversal would halt when there are no cells left that satisfy our criteria. The final result of the function will be a list that includes all the visited cell values in the order of their visitation.
Consider a 3x3 grid:
If we start at the cell with the value '5', we can logically move to either '6' or '8'. Let's say we choose '6'; the only cell that we can now move to is '9'. After this, we have no more moves left that fit our criteria. Hence, the function returns [5, 6, 9].
The first thing we need to do is determine the dimensions of our grid, which is relatively easy in Python with the len() function. We can also establish the directions that our traversal can take. In the context of matrices, when we say we are moving 'up', we are moving one step towards the first row (decreasing the row index). Similarly, moving 'down' corresponds to moving one step towards the last row (increasing the row index), and moving left or right relates to decrementing or incrementing the column index, respectively.
