Count Negative Numbers in a Sorted Matrix

class Solution:
    def countNegatives(self, grid: List[List[int]]) -> int:
        # Naive

        # Keep track of num neg numbers so far
        num_neg_nums = 0

        # Loop through each row
        for row in grid:

            # If first elem in row is neg, whole row is neg
            if row[0] < 0:
                num_neg_nums += len(row)
                continue

            # If last elem in row is pos, whole row is pos
            if row[-1] >= 0:
                continue

            # Binary search to find lowest positive number in that row
            # Initialise bounds
            left_index = 0
            right_index = len(row) - 1
            # Binary search loop
            while left_index <= right_index:

                # Find mid index and number within bounds
                mid_index = (left_index + right_index) // 2
                mid_num = row[mid_index]

                # If mid num is non-negative and next number is negative
                if mid_num >= 0 and row[mid_index + 1] < 0:
                    # Add num neg numbers in row to total
                    num_neg_nums += len(row) - (mid_index + 1)
                    break

                # If mid num is negative, move to the left
                if mid_num < 0:
                    right_index = mid_index - 1

                # If mid num is not negative, move to the right
                else:
                    left_index = mid_index + 1

        # Return total num of neg nums
        return num_neg_nums