Mara Code
Here\'s a step-by-step explanation:\n\nInitialization:\n\ntptr: A pointer used to traverse the list.\nnewNode: Points to the node that will be modified next.\np
**Here\'s a step-by-step explanation:**\n\n**Initialization:**\n**\ntptr:** A pointer used to traverse the list.\nnewNode: Points to the node that will be modified next.\nprev: Keeps track of the previous node before the newNode.\nsum1: Accumulates the sum of values between 0s.\n\n**Traversal:**\n\nThe outer for loop iterates through the list using tptr.\nThe inner while loop sums values until a 0 node is encountered.\n\n**Summing Values:**\n\nInside the while loop, if the current node (tptr) is not null and its value is not 0, its value is added to sum1.\ntptr is then advanced to the next node.\nInserting Sum and Moving Pointers:\n\nOnce a 0 node is encountered (or the end of the list is reached), if sum1 is not 0:\nThe value of newNode is set to sum1.\nprev is updated to newNode.\nnewNode is advanced to its next node.\nsum1 is reset to 0 for the next segment of values.\nFinalizing the List:\n\nAfter the loop, the next pointer of prev (the last valid node) is set to NULL, effectively removing any trailing nodes that were part of the summing process.\nThe modified list, starting from head, is returned.\n\n# Complexity\n- Time complexity:\nO(n)\n\n- Space complexity:\nO(1)\n\n# Code\n```\n\nstruct ListNode* mergeNodes(struct ListNode* head) {\n    struct ListNode *tptr=NULL,*newNode,*prev=NULL;\n    newNode=head;\n    int sum1=0;\n    for(tptr=head;tptr;tptr=tptr->next){\n        while(tptr&&tptr->val!=0){\n            sum1=sum1+tptr->val;\n            tptr=tptr->next;\n        }\n        if(sum1!=0){\n            newNode->val=sum1;\n            prev=newNode;\n            newNode=newNode->next;\n            sum1=0;\n        }\n            \n    }\n    prev->next=NULL;\n    return head;\n}\n```\n\n\n![upVote.jpeg](https://assets.leetcode.com/users/images/07e75afc-bee9-4e46-8d73-5c4bd34a7ee1_1720095144.147385.jpeg)\n
['C']