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1920. Build Array from Permutation 👍

  • Time: $O(n)$
  • Space: $O(1)$
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class Solution {
 public:
  vector<int> buildArray(vector<int>& nums) {
    const int n = nums.size();

    for (int i = 0; i < n; ++i)
      nums[i] += n * (nums[nums[i]] % n);

    for (int i = 0; i < n; ++i)
      nums[i] /= n;

    return nums;
  }
};

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class Solution {
  public int[] buildArray(int[] nums) {
    final int n = nums.length;

    for (int i = 0; i < n; ++i)
      nums[i] += n * (nums[nums[i]] % n);

    for (int i = 0; i < n; ++i)
      nums[i] /= n;

    return nums;
  }
}

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class Solution:
  def buildArray(self, nums: list[int]) -> list[int]:
    n = len(nums)

    for i, num in enumerate(nums):
      nums[i] += n * (nums[num] % n)

    for i in range(n):
      nums[i] //= n

    return nums