Print Boundary Elements of a Matrix in JavaScript ❤️

Matrixes are basic data structures that are frequently used to represent grids or tables of numbers. Gathering and showing the elements that are positioned along a matrix’s edges is the process of printing the matrix’s boundary elements.

There are several approaches in JavaScript to print the boundary elements of a matrix which are as follows:

Table of Content

Using brute force
Using for loop
Using array methods

This method iterates through the entire matrix and checks if the current element is on the first or last row/column. If it is, it prints the element.

Example: “This function prints boundary elements of a 2D matrix, iterating through rows and columns to exclude interior elements. It demonstrates boundary printing with a sample matrix.”

Javascript


                    function printBoundary(matrix) {
    const rows = matrix
        .length;
    if (rows === 0) return;
    const cols = matrix[0]
        .length;

    for (let i = 0; i < rows; i++) {
        for (let j = 0; j < cols; j++) {

            if (i === 0
                ||
                j === 0
                ||
                i === rows - 1
                ||
                j === cols - 1) {
                console.log(matrix[i][j]);
            }
        }
    }
}


const matrix = [
    [1, 2]

];

printBoundary(matrix);

Output

1
2

This method efficiently prints the boundary items without additional checks by iterating through the first and last rows and columns using for loop.

Example:“This function efficiently prints boundary elements of a 2D matrix, showcasing optimized printing steps and providing a sample matrix for demonstration.”

Javascript


                    function printBoundary(matrix) {
    const rows = matrix.length;
    const cols = matrix[0].length;

    if (rows === 0 || cols === 0) {
        return; // Empty matrix
    }

    // Print first row
    for (let i = 0; i < cols; i++) {
        console.log(matrix[0][i]);
    }

    // Print last column (excluding corners)
    for (let i = 1; i < rows; i++) {
        console.log(matrix[i][cols - 1]);
    }

    // Print last row (excluding the first element 
    // which has already been printed)
    if (rows > 1) {
        for (let i = cols - 2; i >= 0; i--) {
            console.log(matrix[rows - 1][i]);
        }
    }

    // Print first column (excluding corners and the last 
    // element which has already been printed)
    if (cols > 1) {
        for (let i = rows - 2; i > 0; i--) {
            console.log(matrix[i][0]);
        }
    }
}
const matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];

printBoundary(matrix);

Output

The code utilizes the `reduce()` method to iterate over each row of the matrix, extracting boundary elements based on their positions. It concatenates the elements into an array, effectively forming the boundary elements. The `forEach()` method is then used to print each boundary element. Overall, this approach demonstrates how array methods can be leveraged to manipulate and extract data from multidimensional arrays efficiently.

Example: Extracting boundary elements from a matrix using array methods like `reduce()` and `forEach().

Javascript


                    function printBoundary(matrix) {
    const boundaryElements = matrix
        .reduce((acc, row, rowIndex) => {
            if (rowIndex === 0
                ||
                rowIndex === matrix.length - 1) {
                return acc
                    .concat(row);
            } else {
                return acc
                    .concat([row[0], row[row.length - 1]]);
            }
        }, []);
    boundaryElements
        .forEach(element => console.log(element));
}

// Example usage
const matrix = [
    [1, 2],
    [3, 4]
]

console.log("Boundary elements using array methods:");
printBoundary(matrix);

Output

Boundary elements using array methods:
1
2
3
4

Print Boundary Elements of a Matrix in JavaScript

Using brute force

Using for loop

Using array methods

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