1. Spiral Traversal of a 2D matrix

Problem:

Given a 2D matrix, traverse all it’s elements in a spiral form.
Referring the below matrix as an input (Red line shows a spiral traversal),

output should be: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Solution:

This implementation is done using C#.NET. Rectangular Matrix is declared using int[,] syntax.

public void DoSpiralTraversal(int[, ]rectArray) {
        if (rectArray != null && rectArray.Length > 0) {
            Console.WriteLine("Doing Spiral Traversal on a 2D array:");

            int noOfElementsTraversed = 0, row_LB = 0, row_UB = rectArray.GetUpperBound(0), col_LB = 0, col_UB =
                    rectArray.GetUpperBound(1), iter;

            while (true) {
                // Move downwards
                for (iter = row_LB; iter = rectArray.Length) {
                    break;
                }

                col_LB++;

                // Move Left to Right
                for (iter = col_LB; iter = rectArray.Length) {
                    break;
                }

                row_UB–-;

                // Move upwards
                for (iter = row_UB; iter >= row_LB; iter–)
                {
                    Console.Write(rectArray[iter, col_UB]+”“);

                    noOfElementsTraversed++;
                }

                if (noOfElementsTraversed >= rectArray.Length) {
                    break;
                }

                col_UB–-;

                // Move right to Left
                for (iter = col_UB; iter >= col_LB; iter–)
                {
                    Console.Write(rectArray[row_LB, iter]+”“);

                    noOfElementsTraversed++;
                }

                if (noOfElementsTraversed >= rectArray.Length) {
                    break;
                }
                
                row_LB++;
            }
        }
    }