<p>You are given the <code>head</code> of a linked list, which contains a series of integers <strong>separated</strong> by <code>0</code>'s. The <strong>beginning</strong> and <strong>end</strong> of the linked list will have <code>Node.val == 0</code>.</p> <p>For <strong>every </strong>two consecutive <code>0</code>'s, <strong>merge</strong> all the nodes lying in between them into a single node whose value is the <strong>sum</strong> of all the merged nodes. The modified list should not contain any <code>0</code>'s.</p> <p>Return <em>the</em> <code>head</code> <em>of the modified linked list</em>.</p> <p> </p> <p><strong>Example 1:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2022/02/02/ex1-1.png" style="width: 600px; height: 41px;" /> <pre> <strong>Input:</strong> head = [0,3,1,0,4,5,2,0] <strong>Output:</strong> [4,11] <strong>Explanation:</strong> The above figure represents the given linked list. The modified list contains - The sum of the nodes marked in green: 3 + 1 = 4. - The sum of the nodes marked in red: 4 + 5 + 2 = 11. </pre> <p><strong>Example 2:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2022/02/02/ex2-1.png" style="width: 600px; height: 41px;" /> <pre> <strong>Input:</strong> head = [0,1,0,3,0,2,2,0] <strong>Output:</strong> [1,3,4] <strong>Explanation:</strong> The above figure represents the given linked list. The modified list contains - The sum of the nodes marked in green: 1 = 1. - The sum of the nodes marked in red: 3 = 3. - The sum of the nodes marked in yellow: 2 + 2 = 4. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li>The number of nodes in the list is in the range <code>[3, 2 * 10<sup>5</sup>]</code>.</li> <li><code>0 <= Node.val <= 1000</code></li> <li>There are <strong>no</strong> two consecutive nodes with <code>Node.val == 0</code>.</li> <li>The <strong>beginning</strong> and <strong>end</strong> of the linked list have <code>Node.val == 0</code>.</li> </ul>