Array help for using two for loops

#1 
var cars = [["A", "B", "C"],["D", "E", "F"],["G", "H", "I"]];
var diag = (cars.length*2) - 1
var result = [];

  for(i = cars.length - 1; i >= 0; i--) {
    for(j = cars.length - 1; j >= 0; j--) {
      const x = i;
      const y = diag - j;
      
        if( x>= 0 && y<= diag) {
            console.log(result)
        }
    }

Can someone help with this? Trying to start from bottom right to top left. I know I need a function too.

#2

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.

Note: Backticks are not single quotes.

markdown_Forums

1 Like
#3

So your j loop, which I assume you want to loop over the INNER arrays, should probably not be comparing to cars.length. Instead, at the first iteration (when i==0), you want to be setting j to cars[0].length-1. At the next iteration, when i==1, you want j to equal cars[1].length-1.

Each sub-array is found at a given index in the cars array. Can you think of a way, inside that inner loop, to get that? Hint: think about i.

#4

Can you explain in detail what you are trying to do here? Can you show an example of the expected output in the console you want to achieve?

#5 
[["A", "B", "C"],
["D", "E", "F"],
["G", "H", "I"]];

[ I, F, H, C, E, G, B, D, A];

Trying to get it to read like that. From bottom right to top left.

#6

That path seems strange to me. Why would you go from H to C?

#7

Because it is going from bottom right to top left and that is the most bottom right after it cycles thru the array that forms a square.

#8

For these kinds of problems, I try to figure out a pattern by mapping out the values based on their indices.

[
  [(0,0), (0,1), (0,2)],
  [(1,0), (1,1), (1,2)],
  [(2,0), (2,1), (2,2)]
];

[(2,2), (1,2), (2,1), (0,2), (1,1), (2,0), (0,1), (1,0), (0,0)]

See if this helps you to better understand the index relationships.

#9