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Grokking the Coding Interview Patterns in C++

Set Matrix Zeroes

Explore how to modify matrices by setting rows and columns to zero when any element is zero, focusing on in-place operations without extra memory allocation. Learn to implement efficient matrix transformations and understand the problem constraints while practicing your coding skills with hands-on exercises.

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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.

C++
usercode > SetMatrixZeros.cpp
#include <iostream>
#include <vector>
#include <queue>
vector<vector<int>> SetMatrixZeros(vector<vector<int>>& mat)
{    
    // Replace this placeholder return statement with your code
    return mat;
}
Set Matrix Zeroes