Transposing Matrices with Kotlin | CodeSignal Learn

Transposing Matrices with Kotlin | CodeSignal Learn

Introduction

Hello there! Are you ready to enhance your programming skills with an exciting exercise using Kotlin ? In this unit, we are delving into the world of matrices . Specifically, we'll be transposing a given matrix. Let's dive into this matrix manipulation game without delay!

Task Statement

Let's dive into the task at hand. Your objective is to write a Kotlin function named transformMatrix() . This function will accept a 2D Int array (which represents a matrix) containing integers as input. Your responsibility is to return another 2D Int array, which is the transposed version of the given matrix. Remember, transposing a matrix involves switching its rows and columns. In other words, all the rows of the original matrix should convert into columns in the transposed matrix, and vice versa. For instance, if the original matrix (input 2D array) is: Kotlin val matrix = arrayOf(intArrayOf(1, 2, 3), intArrayOf(4, 5, 6)) Then the transposed matrix (output 2D array) will be: Kotlin val transposed = arrayOf(intArrayOf(1, 4), intArrayOf(2, 5), intArrayOf(3, 6)) It is crucial for your result to maintain the integrity of the data type in the original matrix. The values in the input matrix are integers, and they should remain integers in the output matrix as well.

Solution Building: Step 1

The initial step in building our solution involves determining the dimensions of the matrix. We need to know the number of rows and columns present in it. In Kotlin, the size properties can provide this information. The number of rows corresponds to the size of the outer array, and the number of columns matches the size of any inner array. Kotlin fun transformMatrix(matrix: Array<IntArray>): Array<IntArray> {val rows = matrix.size val cols = if (rows > 0) matrix[0].size else 0 // If rows > 0, the above line sets cols to the size of the first row, else sets to 0}

Solution Building: Step 2

The next step is to create a "placeholder" for the transposed matrix in alignment with its required dimensions. This will be a new 2D array, but with the number of rows and columns swapped. Initially, we can populate this matrix with all zeros. Kotlin fun transformMatrix(matrix: Array<IntArray>): Array<IntArray> {val rows = matrix.size val cols = if (rows > 0) matrix[0].size else 0 val result = Array(cols) { IntArray(rows) }}

Sign up

Join the 1M+ learners on CodeSignal

Be a part of our community of 1M+ users who develop and demonstrate their skills on CodeSignal

Solution Building: Step 3

It's time to get to the heart of the matter — transposing the matrix. For every element in the original matrix, we want to move it from the i th row and j th column to the j th row and i th column of the transposed matrix. A straightforward nested for-loop can efficiently execute this swap for all elements of the matrix. fun transformMatrix(matrix: Array<IntArray>): Array<IntArray> {val rows = matrix.size val cols = if (rows > 0) matrix[0].size else 0 val result = Array(cols) { IntArray(rows) } for (i in 0 until rows) {for (j in 0 until cols) {result[j][i] = matrix[i][j]}} return result} fun main() {// Initial matrix (2D array) val matrix = arrayOf(intArrayOf(1, 2, 3), intArrayOf(4, 5, 6)) // Call our function on the matrix and output the result val transposed = transformMatrix(matrix) for (row in transposed) {for (elem in row) {print("$elem ")} println()} // Expected output: // 1 4 // 2 5 // 3 6} This step concludes our solution!

Kotlin

fun transformMatrix(matrix: Array<IntArray>): Array<IntArray> {
    val rows = matrix.size
    val cols = if (rows > 0) matrix[0].size else 0
    val result = Array(cols) { IntArray(rows) }

    for (i in 0 until rows) {
        for (j in 0 until cols) {
            result[j][i] = matrix[i][j]
        }
    }
    return result
}

fun main() {
    // Initial matrix (2D array)
    val matrix = arrayOf(
        intArrayOf(1, 2, 3),
        intArrayOf(4, 5, 6)
    )

    // Call our function on the matrix and output the result
    val transposed = transformMatrix(matrix)
    for (row in transposed) {
        for (elem in row) {
            print("$elem ")
        }
        println()
    }
    // Expected output:
    // 1 4 
    // 2 5 
    // 3 6 
}