Leet Code Daily 2024-07-04 - Merge Nodes in Between Zeros

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* mergeNodes(ListNode* head) {
        if (head == nullptr || head->next == nullptr) {
            return nullptr;
        }
        while (head->next != nullptr && head->next->val != 0) {
            head->val += head->next->val;
            head->next = head->next->next;
        }
        head->next = mergeNodes(head->next);
        return head;
    }
};