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: Choose an integer k where 1 <= k <= arr.length. Reverse the sub-array 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. Print out the k-values corresponding to a sequence of pancake flips that sort arr. Example 1: Input: arr = [3,2,4,1] Output: 4, 2, 4, 3 Explanation: We perform 4 pancake flips, with k values 4, 2, 4, and 3. Starting state: arr = [3, 2, 4, 1]. After 1st flip (k = 4): arr = [1, 4, 2, 3] After 2nd flip (k = 2): arr = [4, 1, 2, 3] After 3rd flip (k = 4): arr = [3, 2, 1, 4] After 4th flip (k = 3): arr = [1, 2, 3, 4], which is sorted. Another potential solution is: Output = 3, 4, 2, 3, 1, 2, 1, 1 with a similar explanation. All potential solutions that solve the problem are accepted. Example 2: Input: arr = [1,2,3] Output: [] Explanation: The input is already sorted, so there is no need to flip anything. Note that other answers, such as [3, 3], would also be accepted. Constraints: 1 <= arr.length <= 100 1 <= arr[i] <= arr.length All integers in arr are unique (i.e. arr is a permutation of the integers from 1 to arr.length). ======================================================================================= class Solution { public static void pancakeSort(int[] inputArray) { } private static int find(int[] A, int target) { } private static void flip(int[] A, int index) { } public static void main(String[] args){ int[] arr = {3,2,4,1}; pancakeSort(arr); } }
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:
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Choose an integer k where 1 <= k <= arr.length.
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Reverse the sub-array 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.
Print out the k-values corresponding to a sequence of pancake flips that sort arr.
Example 1:
Input: arr = [3,2,4,1]
Output: 4, 2, 4, 3
Explanation: We perform 4 pancake flips, with k values 4, 2, 4, and 3.
Starting state: arr = [3, 2, 4, 1].
After 1st flip (k = 4): arr = [1, 4, 2, 3]
After 2nd flip (k = 2): arr = [4, 1, 2, 3]
After 3rd flip (k = 4): arr = [3, 2, 1, 4]
After 4th flip (k = 3): arr = [1, 2, 3, 4], which is sorted.
Another potential solution is: Output = 3, 4, 2, 3, 1, 2, 1, 1 with a similar explanation. All potential solutions that solve the problem are accepted.
Example 2:
Input: arr = [1,2,3]
Output: []
Explanation: The input is already sorted, so there is no need to flip anything. Note that other answers, such as [3, 3], would also be accepted.
Constraints:
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1 <= arr.length <= 100
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1 <= arr[i] <= arr.length
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All integers in arr are unique (i.e. arr is a permutation of the integers from 1 to arr.length).
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