Flatten Deeply Nested Array
Given a multi-dimensional array arr
and a depth n
, return a flattened version of that array.
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
. The depth of the elements in the first array are considered to be 0
.
Please solve it without the built-in 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.
/**
* @param {any[]} arr
* @param {number} depth
* @return {any[]}
*/
var flat = function (arr, n) {
if (n === undefined) {
depth = 1;
}
var flattenedArray = [];
for (var i = 0; i < arr.length; i++) {
if (Array.isArray(arr[i]) && n > 0) {
var nestedArray = flat(arr[i], n - 1);
flattenedArray.push(...nestedArray);
} else {
flattenedArray.push(arr[i]);
}
}
return flattenedArray;
};