<p>You are given an <code>m x n</code> matrix of characters <code>box</code> representing a side-view of a box. Each cell of the box is one of the following:</p> <ul> <li>A stone <code>'#'</code></li> <li>A stationary obstacle <code>'*'</code></li> <li>Empty <code>'.'</code></li> </ul> <p>The box is rotated <strong>90 degrees clockwise</strong>, causing some of the stones to fall due to gravity. Each stone falls down until it lands on an obstacle, another stone, or the bottom of the box. Gravity <strong>does not</strong> affect the obstacles' positions, and the inertia from the box's rotation <strong>does not </strong>affect the stones' horizontal positions.</p> <p>It is <strong>guaranteed</strong> that each stone in <code>box</code> rests on an obstacle, another stone, or the bottom of the box.</p> <p>Return <em>an </em><code>n x m</code><em> matrix representing the box after the rotation described above</em>.</p> <p> </p> <p><strong>Example 1:</strong></p> <p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/rotatingtheboxleetcodewithstones.png" style="width: 300px; height: 150px;" /></p> <pre> <strong>Input:</strong> box = [["#",".","#"]] <strong>Output:</strong> [["."], ["#"], ["#"]] </pre> <p><strong>Example 2:</strong></p> <p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/rotatingtheboxleetcode2withstones.png" style="width: 375px; height: 195px;" /></p> <pre> <strong>Input:</strong> box = [["#",".","*","."], ["#","#","*","."]] <strong>Output:</strong> [["#","."], ["#","#"], ["*","*"], [".","."]] </pre> <p><strong>Example 3:</strong></p> <p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/rotatingtheboxleetcode3withstone.png" style="width: 400px; height: 218px;" /></p> <pre> <strong>Input:</strong> box = [["#","#","*",".","*","."], ["#","#","#","*",".","."], ["#","#","#",".","#","."]] <strong>Output:</strong> [[".","#","#"], [".","#","#"], ["#","#","*"], ["#","*","."], ["#",".","*"], ["#",".","."]] </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>m == box.length</code></li> <li><code>n == box[i].length</code></li> <li><code>1 <= m, n <= 500</code></li> <li><code>box[i][j]</code> is either <code>'#'</code>, <code>'*'</code>, or <code>'.'</code>.</li> </ul>