<p>Given a rectangular pizza represented as a <code>rows x cols</code> matrix containing the following characters: <code>'A'</code> (an apple) and <code>'.'</code> (empty cell) and given the integer <code>k</code>. You have to cut the pizza into <code>k</code> pieces using <code>k-1</code> cuts. </p> <p>For each cut you choose the direction: vertical or horizontal, then you choose a cut position at the cell boundary and cut the pizza into two pieces. If you cut the pizza vertically, give the left part of the pizza to a person. If you cut the pizza horizontally, give the upper part of the pizza to a person. Give the last piece of pizza to the last person.</p> <p><em>Return the number of ways of cutting the pizza such that each piece contains <strong>at least</strong> one apple. </em>Since the answer can be a huge number, return this modulo 10^9 + 7.</p> <p> </p> <p><strong>Example 1:</strong></p> <p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/04/23/ways_to_cut_apple_1.png" style="width: 500px; height: 378px;" /></strong></p> <pre> <strong>Input:</strong> pizza = ["A..","AAA","..."], k = 3 <strong>Output:</strong> 3 <strong>Explanation:</strong> The figure above shows the three ways to cut the pizza. Note that pieces must contain at least one apple. </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> pizza = ["A..","AA.","..."], k = 3 <strong>Output:</strong> 1 </pre> <p><strong>Example 3:</strong></p> <pre> <strong>Input:</strong> pizza = ["A..","A..","..."], k = 1 <strong>Output:</strong> 1 </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= rows, cols <= 50</code></li> <li><code>rows == pizza.length</code></li> <li><code>cols == pizza[i].length</code></li> <li><code>1 <= k <= 10</code></li> <li><code>pizza</code> consists of characters <code>'A'</code> and <code>'.'</code> only.</li> </ul>