<h2><a href="https://leetcode.com/problems/count-submatrices-with-all-ones">1628. Count Submatrices With All Ones</a></h2><h3>Medium</h3><hr><p>Given an <code>m x n</code> binary matrix <code>mat</code>, <em>return the number of <strong>submatrices</strong> that have all ones</em>.</p>

<p>&nbsp;</p>

<p><strong class="example">Example 1:</strong></p>

<img alt="" src="https://assets.leetcode.com/uploads/2021/10/27/ones1-grid.jpg" style="width: 244px; height: 245px;" />

<pre>

<strong>Input:</strong> mat = [[1,0,1],[1,1,0],[1,1,0]]

<strong>Output:</strong> 13

<strong>Explanation:</strong>

There are 6 rectangles of side 1x1.

There are 2 rectangles of side 1x2.

There are 3 rectangles of side 2x1.

There is 1 rectangle of side 2x2.

There is 1 rectangle of side 3x1.

Total number of rectangles = 6 + 2 + 3 + 1 + 1 = 13.

</pre>

<p><strong class="example">Example 2:</strong></p>

<img alt="" src="https://assets.leetcode.com/uploads/2021/10/27/ones2-grid.jpg" style="width: 324px; height: 245px;" />

<pre>

<strong>Input:</strong> mat = [[0,1,1,0],[0,1,1,1],[1,1,1,0]]

<strong>Output:</strong> 24

<strong>Explanation:</strong>

There are 8 rectangles of side 1x1.

There are 5 rectangles of side 1x2.

There are 2 rectangles of side 1x3.

There are 4 rectangles of side 2x1.

There are 2 rectangles of side 2x2.

There are 2 rectangles of side 3x1.

There is 1 rectangle of side 3x2.

Total number of rectangles = 8 + 5 + 2 + 4 + 2 + 2 + 1 = 24.

</pre>

<p>&nbsp;</p>

<p><strong>Constraints:</strong></p>

<ul>

<li><code>1 &lt;= m, n &lt;= 150</code></li>

<li><code>mat[i][j]</code> is either <code>0</code> or <code>1</code>.</li>

</ul>