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Grokking the Coding Interview Patterns in Python

Set Matrix Zeroes

Understand how to modify a matrix in place by setting entire rows and columns to zero when any element is zero. Learn to solve this common coding interview problem efficiently without allocating additional space, enhancing your matrix manipulation skills and problem-solving approach.

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Statement

Given a matrix, mat, if any element within the matrix is zero, set that row and column to zero. The performed operations should be in place, i.e., the given matrix is modified directly without allocating another matrix.

Constraints:

  • 1≤1 \le mat.row, mat.col ≤20\le 20
  • −231≤-2^{31} \le mat[i][j] ≤231−1\le 2^{31} - 1

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re are solving the correct problem:

Set Matrix Zeros

1.

What is the correct output if the following matrix is given as input?

matrix=[123456709]matrix = \begin{bmatrix}1 & 2 & 3 \\4 & 5 & 6 \\ 7 & 0 & 9 \end{bmatrix}

A.

matrix=[020406000]matrix = \begin{bmatrix}0 & 2 & 0 \\4 & 0 & 6 \\ 0 & 0 & 0 \end{bmatrix}

B.

matrix=[103406000]matrix = \begin{bmatrix}1 & 0 & 3 \\4 & 0 & 6 \\ 0 & 0 & 0 \end{bmatrix}

C.

matrix=[103406709]matrix = \begin{bmatrix}1 & 0 & 3 \\4 & 0 & 6 \\ 7 & 0 & 9 \end{bmatrix}

D.

matrix=[123456000]matrix = \begin{bmatrix}1 & 2 & 3 \\4 & 5 & 6 \\ 0 & 0 & 0 \end{bmatrix}

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Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
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Try it yourself

Implement your solution in the following coding playground.

Python
usercode > main.py
def set_matrix_zeros(mat):

    

    # Replace this placeholder return statement with your code

    return mat
Set Matrix Zeroes