Question

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place.

Follow up:
Did you use extra space?
A straight forward solution using O(mn) space is probably a bad idea.
A simple improvement uses O(m + n) space, but still not the best solution.
Could you devise a constant space solution?

Answer 1

To solve the matrix zero element challenge in place, the solution uses the first row and column as markers and iterative passes to set rows and columns to zero, achieving constant space complexity.

Step-by-step explanation:

Matrix Zero Element Challenge

To address the given problem of setting an element's entire row and column to 0 in a matrix when the element itself is 0, we can use a constant space solution. To avoid using additional space, we can leverage the first row and column of the matrix itself to keep track of the rows and columns that need to be zeroed out. Here's a step-by-step solution:

1. First, check if the first row and first column need to be zeroed by storing this information in two boolean variables.
2. Iterate through the matrix, and for every element that is 0, set the corresponding element in the first row and first column to 0 to mark that row and column.
3. Using the first row and column as markers, iterate through the rest of the matrix (excluding first row and column) and set elements to 0 if their row or column is marked.
4. Finally, zero out the first row and first column if needed based on the boolean variables set in step 1.

This approach allows us to modify the matrix in place without the need for additional storage beyond the two variables for the first row and column checks.