{ "data": { "question": { "questionId": "2241", "questionFrontendId": "2122", "boundTopicId": null, "title": "Recover the Original Array", "titleSlug": "recover-the-original-array", "content": "
Alice had a 0-indexed array arr consisting of n positive integers. She chose an arbitrary positive integer k and created two new 0-indexed integer arrays lower and higher in the following manner:
lower[i] = arr[i] - k, for every index i where 0 <= i < nhigher[i] = arr[i] + k, for every index i where 0 <= i < nUnfortunately, Alice lost all three arrays. However, she remembers the integers that were present in the arrays lower and higher, but not the array each integer belonged to. Help Alice and recover the original array.
Given an array nums consisting of 2n integers, where exactly n of the integers were present in lower and the remaining in higher, return the original array arr. In case the answer is not unique, return any valid array.
Note: The test cases are generated such that there exists at least one valid array arr.
\n
Example 1:
\n\n\nInput: nums = [2,10,6,4,8,12]\nOutput: [3,7,11]\nExplanation:\nIf arr = [3,7,11] and k = 1, we get lower = [2,6,10] and higher = [4,8,12].\nCombining lower and higher gives us [2,6,10,4,8,12], which is a permutation of nums.\nAnother valid possibility is that arr = [5,7,9] and k = 3. In that case, lower = [2,4,6] and higher = [8,10,12]. \n\n\n
Example 2:
\n\n\nInput: nums = [1,1,3,3]\nOutput: [2,2]\nExplanation:\nIf arr = [2,2] and k = 1, we get lower = [1,1] and higher = [3,3].\nCombining lower and higher gives us [1,1,3,3], which is equal to nums.\nNote that arr cannot be [1,3] because in that case, the only possible way to obtain [1,1,3,3] is with k = 0.\nThis is invalid since k must be positive.\n\n\n
Example 3:
\n\n\nInput: nums = [5,435]\nOutput: [220]\nExplanation:\nThe only possible combination is arr = [220] and k = 215. Using them, we get lower = [5] and higher = [435].\n\n\n
\n
Constraints:
\n\n2 * n == nums.length1 <= n <= 10001 <= nums[i] <= 109arr.Compiled with clang 11 using the latest C++ 17 standard.
Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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