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1909. Remove One Element to Make the Array Strictly Increasing

  • Time: $O(n)$
  • Space: $O(1)$
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class Solution {
 public:
  bool canBeIncreasing(vector<int>& nums) {
    bool removed = false;

    for (int i = 1; i < nums.size(); ++i)
      if (nums[i - 1] >= nums[i]) {
        if (removed)
          return false;
        removed = true;  // Remove nums[i - 1].
        if (i > 1 && nums[i - 2] >= nums[i])
          nums[i] = nums[i - 1];  // Remove nums[i] instead.
      }

    return true;
  }
};

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class Solution {
  public boolean canBeIncreasing(int[] nums) {
    boolean removed = false;

    for (int i = 1; i < nums.length; ++i)
      if (nums[i - 1] >= nums[i]) {
        if (removed)
          return false;
        removed = true; // Remove nums[i - 1].
        if (i > 1 && nums[i - 2] >= nums[i])
          nums[i] = nums[i - 1]; // Remove nums[i] instead.
      }

    return true;
  }
}

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class Solution:
  def canBeIncreasing(self, nums: list[int]) -> bool:
    removed = False

    for i in range(1, len(nums)):
      if nums[i - 1] >= nums[i]:
        if removed:
          return False
        removed = True  # Remove nums[i - 1].
        if i > 1 and nums[i - 2] >= nums[i]:
          nums[i] = nums[i - 1]  # Remove nums[i] instead.

    return True