count-negative-numbers-in-a-sorted-matrix

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Algorithms

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

&nbsp;
Example 1:

<pre>
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.
</pre>

Example 2:

<pre>
Input: grid = [[3,2],[1,0]]
Output: 0
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 100</code></li>
	<li><code>-100 &lt;= grid[i][j] &lt;= 100</code></li>
</ul>

&nbsp;
Follow up: Could you find an <code>O(n + m)</code> solution?

countNegatives

Count Negative Numbers in a Sorted Matrix

Maximum Count of Positive Integer and Negative Integer

maximum-count-of-positive-integer-and-negative-integer

正整数和负整数的最大计数

Array

Binary Search

Matrix

给你一个&nbsp;<code>m&nbsp;* n</code>&nbsp;的矩阵&nbsp;<code>grid</code>，矩阵中的元素无论是按行还是按列，都以非严格递减顺序排列。&nbsp;请你统计并返回&nbsp;<code>grid</code>&nbsp;中 负数 的数目。

&nbsp;

示例 1：

<pre>
输入：grid = [[4,3,2,-1],[3,2,1,-1],[1,1,-1,-2],[-1,-1,-2,-3]]
输出：8
解释：矩阵中共有 8 个负数。
</pre>

示例 2：

<pre>
输入：grid = [[3,2],[1,0]]
输出：0
</pre>

&nbsp;

提示：

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 100</code></li>
	<li><code>-100 &lt;= grid[i][j] &lt;= 100</code></li>
</ul>

&nbsp;

进阶：你可以设计一个时间复杂度为 <code>O(n + m)</code> 的解决方案吗？