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2625. Flatten Deeply Nested Array
Description
Given a multidimensional array arr
and a depth n
, return a flattened version of that array.
A multidimensional array is a recursive data structure that contains integers or other multidimensional arrays.
A flattened array is a version of that array with some or all of the subarrays removed and replaced with the actual elements in that subarray. This flattening operation should only be done if the current depth of nesting is less than n
. The depth of the elements in the first array are considered to be 0
.
Please solve it without the builtin Array.flat
method.
Example 1:
Input arr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]] n = 0 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:
Input arr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]] n = 1 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:
Input arr = [[1, 2, 3], [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]] n = 2 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 <= 10^{5}
0 <= count of subarrays in arr <= 10^{5}
maxDepth <= 1000
1000 <= each number <= 1000
0 <= n <= 1000
Solutions

type MultiDimensionalArray = (number  MultiDimensionalArray)[]; var flat = function ( arr: MultiDimensionalArray, n: number, ): MultiDimensionalArray { if (n <= 0) { return arr; } const ans: MultiDimensionalArray = []; for (const x of arr) { if (Array.isArray(x)) { ans.push(...flat(x, n  1)); } else { ans.push(x); } } return ans; };