Medium
Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties:
- Integers in each row are sorted from left to right.
- The first integer of each row is greater than the last integer of the previous row.
Example 1:
Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3
Output: true
Example 2:
Input: matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13
Output: false
Constraints:
m == matrix.lengthn == matrix[i].length1 <= m, n <= 100-104 <= matrix[i][j], target <= 104
defmodule Solution do
@spec search_matrix(matrix :: [[integer]], target :: integer) :: boolean
def search_matrix(matrix, target) do
matrix = matrix |> Enum.map(&List.to_tuple/1) |> List.to_tuple()
binary_search(matrix, 0, tuple_size(matrix) * tuple_size(elem(matrix, 0)) - 1, target)
end
defp binary_search(_matrix, left, right, _target) when left > right, do: false
defp binary_search(matrix, left, right, target) do
mid = div(right + left, 2)
cols = matrix |> elem(0) |> tuple_size()
mid_elem = matrix |> elem(div(mid, cols)) |> elem(rem(mid, cols))
cond do
mid_elem > target -> binary_search(matrix, left, right - 1, target)
mid_elem < target -> binary_search(matrix, mid + 1, right, target)
mid_elem == target -> true
end
end
end