LeetCode in Elixir

35. Search Insert Position

Easy

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You must write an algorithm with O(log n) runtime complexity.

Example 1:

Input: nums = [1,3,5,6], target = 5

Output: 2

Example 2:

Input: nums = [1,3,5,6], target = 2

Output: 1

Example 3:

Input: nums = [1,3,5,6], target = 7

Output: 4

Example 4:

Input: nums = [1,3,5,6], target = 0

Output: 0

Example 5:

Input: nums = [1], target = 0

Output: 0

Constraints:

• 1 <= nums.length <= 104
• -104 <= nums[i] <= 104
• nums contains distinct values sorted in ascending order.
• -104 <= target <= 104

Solution

defmodule Solution do
  @spec search_insert(nums :: [integer], target :: integer) :: integer
  def search_insert(nums, target) do
    search_insert(nums, target, 0, length(nums) - 1)
  end

  defp search_insert(nums, target, lo, hi) when lo <= hi do
    mid = div(lo + hi, 2)

    cond do
      target == Enum.at(nums, mid) ->
        mid

      target < Enum.at(nums, mid) ->
        search_insert(nums, target, lo, mid - 1)

      target > Enum.at(nums, mid) ->
        search_insert(nums, target, mid + 1, hi)
    end
  end

  defp search_insert(_, _, lo, _) do
    lo
  end
end

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