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Decode the Coding Interview in Scala: Real-World Examples

Spiral Matrix

Explore the spiral matrix traversal technique to return all elements of an m by n matrix in clockwise order. Understand the layer-by-layer iteration method, coordinate management, and analyze the time and space complexities of this approach.

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Description

Given an m * n matrix, you have to return all the matrix elements in spiral order. The spiral order signifies traversing the matrix in clockwise order.

Let’s review the spiral order below:

Coding exercise

Scala
import scala.collection.mutable.ListBuffer
object Solution{
  def spiralOrder(matrix: Array[Array[Int]]): List[Int] = {
    //write your code here
     List[Int]()
  }
}
Spiral Matrix

Solution

To solve this problem, we will use a layer by layer approach. In this approach, we iterate over the outer layers’ elements in clockwise order, followed by the inner layer’s elements.

For each layer, we will start from the top left corner and iterate over the elements in that layer. We define the top-left coordinates, say (r1, c1) and bottom-right coordinates, say (r2, c2).

As we explore the layers in clockwise order, we have to:

  1. Iterate the top row, (r1, c), where c ranges from c1 ...