LeetCode：Count Negative Numbers in a Sorted Matrix

Question

Given a m x n matrix grid which is sorted in non-increasing order both row-wise and column-wise, return the number of negative numbers in grid.

Example 1:

Input: grid = [[4,3,2,-1],[3,2,1,-1],[1,1,-1,-2],[-1,-1,-2,-3]]

Output: 8

Explanation: There are 8 negatives number in the matrix.

Example 2:

Input: grid = [[3,2],[1,0]]

Output: 0

Example 3:

Input: grid = [[1,-1],[-1,-1]]

Output: 3

Solution #1

def count_negatives(grid)
  counter = 0
  grid.flatten.each do |num|
    counter += 1 if num.negative?
  end
  counter
end

Solution #2

def count_negatives(grid)
  grid.flatten.select { |n| n.negative? }.count
end