2299 Merge Nodes In Between Zeros

Merge Nodes in Between Zeros

You are given the head of a linked list, which contains a series of integers separated by 0’s. The beginning and end of the linked list will have Node.val == 0.

For every **two consecutive 0’s, **merge all the nodes lying in between them into a single node whose value is the sum of all the merged nodes. The modified list should not contain any 0’s.

Return the head of the modified linked list.

 

Example 1:

**Input:** head = [0,3,1,0,4,5,2,0]
**Output:** [4,11]
**Explanation:** 
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.

Example 2:

**Input:** head = [0,1,0,3,0,2,2,0]
**Output:** [1,3,4]
**Explanation:** 
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.

 

Constraints:

The number of nodes in the list is in the range [3, 2 * 105].
0 <= Node.val <= 1000
There are **no** two consecutive nodes with Node.val == 0.
The **beginning** and **end** of the linked list have Node.val == 0.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */

int merge(struct ListNode* temp1, struct ListNode* temp2){
    int s = 0;
    struct ListNode* temp3 = temp1->next;
    while(temp3 != temp2){
        //printf("%d", temp3->val);
        s += (temp3->val);
        temp3 = temp3->next;
    }
    
    return s;

}

struct ListNode* mergeNodes(struct ListNode* head) {
    struct ListNode* temp1 = head;
    struct ListNode* temp2 = head;
    struct ListNode* result = malloc(sizeof(struct ListNode)); 
    struct ListNode* result2 = result; 
    struct ListNode* result3 = result; 
    while(temp2 != NULL) {
        //printf("%d %d\n", temp1->val, temp2->val);
        if (temp1->val != 0 && temp2->val != 0) {
            
            temp1 = temp1->next;
            temp2 = temp2->next;
            continue;
        }

        if (temp1->val != 0 ){
            temp1 = temp1->next;
            continue;
        }

        if (temp2->val != 0) {
            temp2 = temp2->next;
            continue;
        }

        if (temp1 == temp2 && temp1->val == 0) {
            temp2 = temp2->next;
            continue;
        }

        if (temp1->val == 0 && temp2->val == 0) {
            //merge
            
            int s = merge(temp1, temp2);
            //printf("%d--\n", s);
            result2->val = s;
            result2->next = malloc(sizeof(struct ListNode));
            result3 = result2;
            result2 = result2->next;
            temp1 = temp1->next;
            temp2 = temp2->next;
            //printf("%d --%d\n", temp1->val, temp2->val);
            
        }

    }
    result3->next= NULL;
    
    

    return result;
}