Sums Between Zeros

Medium

You are given a singly linked list head of non-negative integers. The list starts and ends with a zero, and the zeros split it into blocks: between any two neighbouring zeros there is at least one non-zero value. Replace every block with a single node holding the sum of that block, and drop the zeros. Return the head of the new list: the block sums in their original order.

Example 1

head=list_node([0, 2, 7, 0, 5, 0]) → [9, 5]

Between the first two zeros 2 + 7 = 9, between the second and third there is just 5. Answer: [9, 5].

Example 2

head=list_node([0, 4, 4, 4, 4, 0]) → [16]

There is a single block with sum 16.

Example 3

head=list_node([0, 1, 0, 30, 0, 6, 1, 0]) → [1, 30, 7]

Constraints

The list has between 3 and 2·10⁵ nodes
0 ≤ Node.val ≤ 1000
The first and last nodes are 0
No two zeros are adjacent

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Topics

Linked List Simulation

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Input

head=list_node([0, 2, 7, 0, 5, 0])

Expected

[9, 5]

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