Matrix is one of the under-rated topic for coding interviews but Matrix
coding problems are not that easy to solve and In this article, we'll
see some of the popular Matrix coding problems for coding interviews. I
actually learned a lot by solving Matrix related problems. I still remember
the first Matrix based problem I solve was about
how to multiply two matrices in Java
and I learned a lot about multi-dimensional array and nested loop in Java by
solving that problem. The second problem I took was about transposing Matrix
and that was also quite challenging for me at that time but helped me to
further solidify my knowledge about loops and array in Java.

Every since then I have always looked for interesting Matrix based coding
problems and today, I am going to share a couple of gems with you. You can
use them to test your programming and coding skills.

By the way, If you are preparing for coding interview or looking for coding
problems just want to improve your programming skills then you have come to
the right place. In the past, I have shared coding problems on
array,
linked list,
binary tree,
dynamic programming,
system design,
recursion, and
data structures
in general and in this article I will cover Matrices.

##
__10 Matrix based Coding Problems for Practices__

Without wasting anymore of your time, here is a list of Matrix based coding
problems for practice. You can use these Matrix coding questions to not only
prepare for programming job interviews but also for improving your coding
skills. I have included both beginner, medium and difficult level Matrix
questions in this list. Let me know how many you an solve without getting
any help on Internet.

**1. Vertical Flip Matrix Problem **

Given an m x n 2D image matrix where each integer represents a pixel, write
a method flipVerticalAxis to flip it in-place along its vertical axis.

Examples

[[1, 0],

[1, 0]]

->

[[0, 1],

[0, 1]]

###
**2. Horizontal Flip Matrix Problem **

Given an m x n 2D image matrix where each integer represents a pixel, write
a method flipHorizontalAxis to flip it in-place along its horizontal axis.

Examples

[[1, 0],

[0, 1]]

->

[[0, 1],

[1, 0]]

###
**3. Transpose a Given Matrix [Solution]**

You are given a square 2D image matrix where each integer represents a
pixel. Write a method transposeMatrix to transform the matrix into its
transpose - in-place. The transpose of a matrix is a matrix which is formed
by turning all the rows of the source matrix into columns and vice-versa…

Examples

[[1, 2, 3, 4],

[5, 6, 7, 8],

[9, 0, 1, 2],

[3, 4, 5, 0]]

->

[[1, 5, 9, 3],

[2, 6, 0, 4],

[3, 7, 1, 5],

[4, 8, 2, 0]]

### 4. Rotate a given Matrix in Java

Given an image represented by an NxN matrix, where each pixel in the image
is 4 bytes, write a method rotate to rotate the image by 90 degrees in
place.

Examples

[[1, 2, 3, 4],

[5, 6, 7, 8],

[9, 0, 1, 2],

[3, 4, 5, 6]]

->

[[3, 9, 5, 1],

[4, 0, 6, 2],

[5, 1, 7, 3],

[6, 2, 8, 4]]

### 5. Boggle Search Problem

You’re given a 2D Boggle Board which contains an m x n matrix of chars -
char[][] board, and a String - word. Write a method - boggleSearch that
searches the Boggle Board for the presence of the input word. Words on the
board can be constructed with sequentially adjacent letters, where adjacent
letters are horizontal or vertical neighbors (not diagonal). Also, each
letter on the Boggle Board must be used only once.

Examples

Input Board :

[

[A, O, L],

[D, E, L],

[G, H, I]

]

Word: "HELLO"

Output: true

### 6. Zero Matrix Problem

Write a method zeroMatrix with an algorithm such that if an element in a MxN
matrix is 0, its entire row and column are set to 0. Matrix should be
changed in place.

Examples

[[1, 2, 3, 4],

[5, 6, 7, 8],

[9, 0, 1, 2],

[3, 4, 5, 0]]

->

[[1, 0, 3, 0],

[5, 0, 7, 0],

[0, 0, 0, 0],

[0, 0, 0, 0]]

### 7. Count Paths in Given Matrix

You’re given a game board that has m x n squares on it, represented by an m
x n array. Write a method countPaths that takes in m and n and returns the
number of possible paths from the top left corner to the bottom right
corner. Only down and right directions of movement are permitted.

Examples

countPaths(m = 2, n = 2) => 2

as on the following 2x2 Board, the two paths are
A->C->D and A->B->D

A B

C D

### 8. Matrix Max Sum Path Problem

Given an m x n matrix filled with non-negative integers, find the maximum
sum along a path from the top-left of the grid to the bottom-right. Return
this maximum sum. The direction of movement is limited to right and down.

Examples

[[1, 2, 3],

[4, 5, 6], -> 29 (1 + 4 + 7 + 8 + 9)

[7, 8, 9]]

### 9. Largest Square Matrix Problem

Given a two dimensional matrix made up of 0's and 1's, write a method
largestSquare to find the largest square containing all 1’s and return its
area.

The area is simply the sum of all integers enclosed in the square.

Example

Input Matrix :

1101 xxxx 11xx

1101 => 11xx or 11xx

1111 11xx xxxx

Output : 4

### 10. Spiral Matrix Problem

In this problem, you are given an m x n matrix and you need to return all
elements of the matrix in spiral order. This is a medium level Matrix
problem.

Output: [1,2,3,6,9,8,7,4,5]

Here is an example of Spiral order in Matrix:

That's all about

**common matrix based coding problems for programmers and developers.**You can use these questions to not just prepare for coding interviews but also to improve your programming and coding skills. If you are a beginner then Matrix based problems are good to improve your knowledge about loops and multi-dimensional array. They are really good to improve your coding sense as well.
## No comments :

## Post a Comment