C++ easy approach for beginners with diagram
\n\n\n```\n    ListNode mergeNodes(ListNode head) {\n        ListNode temp = head->next;\n        ListNode one = head->next;\n        ListNode *two = head->next
![image](https://assets.leetcode.com/users/images/a265d01a-6f11-4fe1-aa9b-0ddf91a004e3_1645947685.9593856.jpeg)\n\n\n```\n    ListNode* mergeNodes(ListNode* head) {\n        ListNode *temp = head->next;\n        ListNode *one = head->next;\n        ListNode *two = head->next;\n        while(two->next)\n        {   \n            two = two->next;\n            if(two->next == NULL){\n                one->next = NULL;\n                return temp;\n            }\n            if(two->val == 0){\n                two = two->next;\n                one->next = two;\n                one = one->next;  \n            }\n            else{\n                one->val+=two->val;\n            }\n        }\n return temp;       \n    }
[]