# Flatten Deeply Nested Arrays

In this lab, you will be tasked to create a function called `flat`

that accepts a deeply nested **multi-dimensional** array `arr`

and a depth value `n`

. The function must return a **flattened** version of that array based on the given depth `n`

. The depth at which elements should be flattened depends on the depth value `n`

. The depth of the elements in the first array are considered to be `0`

. You must solve this problem without using the built-in `Array.flat`

method.

A **multi-dimensional** array is a recursive data structure that contains integers or other **multi-dimensional** arrays.

A **flattened** array is a version of that array with some or all of the sub-arrays removed and replaced with the actual elements in that sub-array. This flattening operation should only be done if the current depth of nesting is less than `n`

.

## Examples

**Example 1:**

`const arr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]; const n = 0; const result = flat(arr, n); console.log(result); // Output: [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]`

**Explanation:** Passing a depth of `n=0`

will always result in the original array. This is because the smallest possible depth of a subarray (0) is not less than `n=0`

. Thus, no subarray should be flattened.

**Example 2:**

`const arr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]; const n = 1; const result = flat(arr, n); console.log(result); // Output: [1, 2, 3, 4, 5, 6, 7, 8, [9, 10, 11], 12, 13, 14, 15]`

**Explanation:** The subarrays starting with 4, 7, and 13 are all flattened. This is because their depth of 0 is less than 1. However, `[9, 10, 11]`

remains unflattened because its depth is 1.

**Example 3:**

`const arr = [[1, 2, 3], [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]; const n = 2; const result = flat(arr, n); console.log(result); // Output: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]`

**Explanation:** The maximum depth of any subarray is 1. Thus, all of them are flattened.

**Constraints:**

`0 <= count of numbers in arr <= 105`

`0 <= count of subarrays in arr <= 105`

`maxDepth <= 1000`

`-1000 <= each number <= 1000`

`0 <= n <= 1000`