Boundry Traversal of the Matrix

Question – You are given a matrix of dimensions n x m. The task is to perform boundary traversal on the matrix in a clockwise manner.

Example

Given Input: n = 4, m = 4

matrix[][] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15,16}}

Expected Output: 1 2 3 4 8 12 16 15 14 13 9 5

Logic

1. Traverse the top row
2. Traverse the last column
3. Traverse the bottom row
4. Traverse the bottom row

Code

static ArrayList<Integer> boundaryTraversal(int matrix[][], int n, int m)
{
    // Create a list to store the boundary elements
    ArrayList<Integer> list = new ArrayList<>();

    // Get the number of rows and columns in the matrix
    int rows = matrix.length;
    int cols = matrix[0].length;

    // Traverse the top row from left to right
    for (int i = 0; i < cols; i++) {
        list.add(matrix[0][i]);
    }

    // Traverse the last column from top to bottom
    for (int i = 1; i < rows; i++) {
        list.add(matrix[i][cols - 1]);
    }

    // Traverse the bottom row from right to left
    if (rows > 1) {
        for (int i = cols - 2; i >= 0; i--) {
            list.add(matrix[rows - 1][i]);
        }
    }

    // Traverse the first column from bottom to top 
    if (cols > 1) {
        for (int i = rows - 2; i > 0; i--) {
            list.add(matrix[i][0]);
        }
    }

    // Return the list containing the boundary elements
    return list;
}