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2717. Semi-Ordered Permutation 👍

  • Time: $O(n)$
  • Space: $O(1)$
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class Solution {
 public:
  int semiOrderedPermutation(vector<int>& nums) {
    const int n = nums.size();
    const int index1 = find(nums.begin(), nums.end(), 1) - nums.begin();
    const int indexN = find(nums.begin(), nums.end(), n) - nums.begin();
    return index1 + (n - 1 - indexN) - (index1 > indexN ? 1 : 0);
  }
};

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class Solution {
  public int semiOrderedPermutation(int[] nums) {
    final int n = nums.length;
    int index1 = -1;
    int indexN = -1;
    for (int i = 0; i < nums.length; ++i) {
      if (nums[i] == 1)
        index1 = i;
      else if (nums[i] == n)
        indexN = i;
    }
    return index1 + (n - 1 - indexN) - (index1 > indexN ? 1 : 0);
  }
}

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class Solution:
  def semiOrderedPermutation(self, nums: list[int]) -> int:
    n = len(nums)
    index1 = nums.index(1)
    indexN = nums.index(n)
    return index1 + (n - 1 - indexN) - int(index1 > indexN)