Write a function that accepts a multi-dimensional array arr and a depth n, and returns a flattened version of that array.
A multi-dimensional array is a recursive data structure that contains integers or other multi-dimensional arrays.
\r\n\r\nA 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 greater 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.
\r\n
Example 1:
\r\n\r\n\r\nInput\r\narr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\r\nn = 0\r\nOutput\r\n[1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\r\n\r\nExplanation\r\nPassing 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.\r\n\r\n
Example 2:
\r\n\r\n\r\nInput\r\narr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\r\nn = 1\r\nOutput\r\n[1, 2, 3, 4, 5, 6, 7, 8, [9, 10, 11], 12, 13, 14, 15]\r\n\r\nExplanation\r\nThe 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.\r\n\r\n
Example 3:
\r\n\r\n\r\nInput\r\narr = [[1, 2, 3], [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\r\nn = 2\r\nOutput\r\n[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]\r\n\r\nExplanation\r\nThe maximum depth of any subarray is 1. Thus, all of them are flattened.\r\n\r\n
\r\n
Constraints:
\r\n\r\n0 <= count of numbers in arr <= 1050 <= count of subarrays in arr <= 105maxDepth <= 1000-1000 <= each number <= 10000 <= n <= 1000请你编写一个函数，它接收一个 多维数组 arr 和它的深度 n ，并返回该数组的 扁平化 后的结果。
多维数组 是一种包含整数或其他 多维数组 的递归数据结构。
\n\n数组 扁平化 是对数组的一种操作，定义是将原数组部分或全部子数组删除，并替换为该子数组中的实际元素。只有当嵌套的数组深度大于 n 时，才应该执行扁平化操作。第一层数组中元素的深度被认为是 0。
请在没有使用内置方法 Array.flat 的前提下解决这个问题。
\n\n
示例 1：
\n\n\n输入\narr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\nn = 0\n输出\n[1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\n\n解释\n传递深度 n=0 的多维数组将始终得到原始数组。这是因为 子数组(0) 的最小可能的深度不小于 n=0 。因此，任何子数组都不应该被平面化。\n\n\n
示例 2：
\n\n\n输入\narr = [1, 2, 3, [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\nn = 1\n输出\n[1, 2, 3, 4, 5, 6, 7, 8, [9, 10, 11], 12, 13, 14, 15]\n\n解释\n以 4 、7 和 13 开头的子数组都被扁平化了，这是因为它们的深度为 0 ， 而 0 小于 1 。然而 [9,10,11] 其深度为 1 ，所以未被扁平化。\n\n
示例 3：
\n\n\n输入\narr = [[1, 2, 3], [4, 5, 6], [7, 8, [9, 10, 11], 12], [13, 14, 15]]\nn = 2\n输出\n[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]\n\n解释\n所有子数组的最大深度都为 1 。因此，它们都被扁平化了。\n\n
\n\n
提示：
\n\n0 <= arr 的元素个数 <= 1050 <= arr 的子数组个数 <= 105maxDepth <= 1000-1000 <= each number <= 10000 <= n <= 1000\\u7248\\u672c\\uff1a \\u60a8\\u7684\\u4ee3\\u7801\\u5728\\u6267\\u884c\\u65f6\\u5c06\\u5e26\\u4e0a lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 datastructures-js\\/priority-queue@5.3.0<\\/a> \\u548c datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"],\"typescript\":[\"TypeScript\",\" TypeScript 4.5.4<\\/p>\\r\\n\\r\\n Compile Options: --alwaysStrict --strictBindCallApply --strictFunctionTypes --target ES2020<\\/p>\\r\\n\\r\\n lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 datastructures-js\\/priority-queue@5.3.0<\\/a> \\u548c datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"]}",
"book": null,
"isSubscribed": false,
"isDailyQuestion": false,
"dailyRecordStatus": null,
"editorType": "CKEDITOR",
"ugcQuestionId": null,
"style": "LEETCODE",
"exampleTestcases": "[1,2,3,[4,5,6],[7,8,[9,10,11],12],[13,14,15]]\n0\n[1,2,3,[4,5,6],[7,8,[9,10,11],12],[13,14,15]]\n1\n[1,2,3,[4,5,6],[7,8,[9,10,11],12],[13,14,15]]\n2",
"__typename": "QuestionNode"
}
}
}Node.js 16.13.2<\\/code><\\/p>\\r\\n\\r\\n--harmony<\\/code> \\u6807\\u8bb0\\u6765\\u5f00\\u542f \\u65b0\\u7248ES6\\u7279\\u6027<\\/a>\\u3002<\\/p>\\r\\n\\r\\n