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
[0] -> [3] -> [1] -> [0] -> [4] -> [5] -> [2] -> [0] -> null
---
[4] -> [11] -> null
Inputhead = [0,3,1,0,4,5,2,0]
Output[4,11]
The modified list contains sums 3 + 1 = 4 and 4 + 5 + 2 = 11.
Example 2
[0] -> [1] -> [0] -> [3] -> [0] -> [2] -> [2] -> [0] -> null
---
[1] -> [3] -> [4] -> null
Inputhead = [0,1,0,3,0,2,2,0]
Output[1,3,4]
The modified list contains sums 1 = 1, 3 = 3, and 2 + 2 = 4.

Constraints

  • The number of nodes in the list is in the range [3, 2 * 10^5].
  • 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.

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