leetcode1351. Count Negative Numbers in a Sorted Matrix

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: 8Explanation: There are 8 negatives number in the matrix.

Example 2:

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

Constraints:

• m == grid.length

• n == grid[i].length

• 1 <= m, n <= 100

• -100 <= grid[i][j] <= 100

正常要O(n+m)的话，要二分法了，但是太懒了。。。

Runtime: 2 ms, faster than 21.57% of Java online submissions for Count Negative Numbers in a Sorted Matrix.

Memory Usage: 47.9 MB, less than 39.58% of Java online submissions for Count Negative Numbers in a Sorted Matrix.