Good evening! Here's our prompt for today.

Diagonal Matrix Traversal

We are given a matrix with m rows and n columns. For example:

1[
2  [1, 2, 3],
3  [4, 5, 6], 
4  [7, 8, 9]
5]  

Our goal is to traverse the matrix diagonally and return the elements in that order.

What does "diagonal" mean? It means we want to go through the matrix diagonally like this:

So we start at the top left, go right, then down and left in a zig-zag.

Key Points

• We are given a 2D matrix with m rows and n columns
• We need to traverse it diagonally
• Return the elements in an array in diagonal order

Constraints

• m = number of rows in matrix
• n = number of columns in matrix
• 1 <= m, n <= 104 (1 to 10,000)
• 1 <= m * n <= 104
• Matrix values are integers between -105 and 105

So in summary, we need to take a 2D matrix and figure out how to traverse it diagonally, returning the values in that order.

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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var assert = require('assert');

​

function find_diagonal_order(matrix) {

    //fill in the solution

    return matrix

}

​

​

try {

    assert.deepEqual(find_diagonal_order([

        [1, 2, 3],

        [4, 5, 6],

        [7, 8, 9]

    ]), [1, 2, 4, 7, 5, 3, 6, 8, 9]);

​

    console.log('PASSED: ' + "find_diagonal_order([[1,2,3],[4,5,6],[7,8,9]]) should return `[1,2,4,7,5,3,6,8,9]`");

} catch (err) {

    console.log(err);

}

​

try {

    assert.deepEqual(find_diagonal_order([

        [1, 2],

        [3, 4]

    ]), [1, 2, 3, 4]);

​

    console.log('PASSED: ' + "find_diagonal_order([[1,2],[3,4]]) should return `[1,2,3,4]`");

} catch (err) {

    console.log(err);

Here's how we would solve this problem...

How do I use this guide?