1351. Count Negative Numbers in a Sorted Matrix

https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix

Description

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

Example 4:

**Input:** grid = [[-1]]
**Output:** 1

Constraints:

• m == grid.length

• n == grid[i].length

• 1 <= m, n <= 100

• -100 <= grid[i][j] <= 100

Follow up: Could you find an O(n + m) solution?

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