Search⌘ K
AI Features
Home
Courses
Grokking the Coding Interview Patterns

Set Matrix Zeroes

Explore how to set entire rows and columns to zero within a matrix in place, directly modifying the given structure. This lesson helps you grasp the logic of matrix transformations without additional memory allocation, preparing you for real coding interviews involving matrix manipulation.

We'll cover the following...

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}

1 / 3

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.
1
2
3
4
5

Try it yourself

Implement your solution in the following coding playground.

Java
usercode > SetMatrixZeros.java
import java.util.*;
public class SetMatrixZeros{
   public static int[][] setMatrixZeros(int[][] mat) {
      
      // Replace this placeholder return statement with your code
      return mat;
   }
}
Set Matrix Zeroes