Given an array of integers arr, sort the array by performing a series of pancake flips.
In one pancake flip we do the following steps:
\n\nk where 1 <= k <= arr.length.arr[0...k-1] (0-indexed).For example, if arr = [3,2,1,4] and we performed a pancake flip choosing k = 3, we reverse the sub-array [3,2,1], so arr = [1,2,3,4] after the pancake flip at k = 3.
Return an array of the k-values corresponding to a sequence of pancake flips that sort arr. Any valid answer that sorts the array within 10 * arr.length flips will be judged as correct.
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Example 1:
\n\n\nInput: arr = [3,2,4,1]\nOutput: [4,2,4,3]\nExplanation: \nWe perform 4 pancake flips, with k values 4, 2, 4, and 3.\nStarting state: arr = [3, 2, 4, 1]\nAfter 1st flip (k = 4): arr = [1, 4, 2, 3]\nAfter 2nd flip (k = 2): arr = [4, 1, 2, 3]\nAfter 3rd flip (k = 4): arr = [3, 2, 1, 4]\nAfter 4th flip (k = 3): arr = [1, 2, 3, 4], which is sorted.\n\n\n
Example 2:
\n\n\nInput: arr = [1,2,3]\nOutput: []\nExplanation: The input is already sorted, so there is no need to flip anything.\nNote that other answers, such as [3, 3], would also be accepted.\n\n\n
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Constraints:
\n\n1 <= arr.length <= 1001 <= arr[i] <= arr.lengtharr are unique (i.e. arr is a permutation of the integers from 1 to arr.length).给你一个整数数组 arr ，请使用 煎饼翻转 完成对数组的排序。
一次煎饼翻转的执行过程如下：
\n\nk ，1 <= k <= arr.lengtharr[0...k-1]（下标从 0 开始）例如，arr = [3,2,1,4] ，选择 k = 3 进行一次煎饼翻转，反转子数组 [3,2,1] ，得到 arr = [1,2,3,4] 。
以数组形式返回能使 arr 有序的煎饼翻转操作所对应的 k 值序列。任何将数组排序且翻转次数在 10 * arr.length 范围内的有效答案都将被判断为正确。
\n\n
示例 1：
\n\n\n输入：[3,2,4,1]\n输出：[4,2,4,3]\n解释：\n我们执行 4 次煎饼翻转，k 值分别为 4，2，4，和 3。\n初始状态 arr = [3, 2, 4, 1]\n第一次翻转后（k = 4）：arr = [1, 4, 2, 3]\n第二次翻转后（k = 2）：arr = [4, 1, 2, 3]\n第三次翻转后（k = 4）：arr = [3, 2, 1, 4]\n第四次翻转后（k = 3）：arr = [1, 2, 3, 4]，此时已完成排序。 \n\n\n
示例 2：
\n\n\n输入：[1,2,3]\n输出：[]\n解释：\n输入已经排序，因此不需要翻转任何内容。\n请注意，其他可能的答案，如 [3，3] ，也将被判断为正确。\n\n\n
\n\n
提示：
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