C++ || Easy-To-Understand.
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n/**\n * Definition for singly-linked list.\n * struct ListNode {\n *     int val;\n *     ListNode *next;\n *     ListNode() : val(0), next(nullptr) {}\n *     ListNode(int x) : val(x), next(nullptr) {}\n *     ListNode(int x, ListNode *next) : val(x), next(next) {}\n * };\n */\nclass Solution {\npublic:\n    ListNode* mergeNodes(ListNode* head) {\n        ListNode* dummy=new ListNode(0);\n        ListNode* node=dummy;\n        ListNode* temp=head;\n        temp=temp->next;\n        int sum=0;\n        while(temp!=NULL){\n            while(temp->val!=0){\n                sum+=temp->val;\n                temp=temp->next;\n                }\n            node->next=new ListNode(sum);\n            node=node->next;\n            temp=temp->next;\n            sum=0;\n        }\n        return dummy->next;\n    }\n};\n\nif it helps Plzz don\'t Forget to upvote it :)\n```
['Linked List', 'C++']