Merge Nodes in Between Zeros LeetCode solution in Java

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/**
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 * Definition for singly-linked list. public class ListNode { int val; ListNode next; ListNode() {}
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 * ListNode(int val) { this.val = val; } ListNode(int val, ListNode next) { this.val = val;
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 * this.next = next; } }
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 */
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class Solution {
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  public ListNode mergeNodes(ListNode head) {
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    ListNode newList = new ListNode(0);
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    ListNode newHead = newList;
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    ListNode newtemp = newList;
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    /*---------------------------------------------------------------*/
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    ListNode temp = head.next;
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    int sum = 0;
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    if (head == null && head.next == null) return head;
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    /*---------------------------------------------------------------*/
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    while (temp != null) { // traverse linkelist
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      sum += temp.val; // sum elements until zero
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      if (temp.val == 0) {
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        ListNode node = new ListNode(sum); // create a new node;
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        newtemp.next = node; // connect with dummy node which is created initially
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        newtemp = newtemp.next; // shift pointer to newly created node
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        sum = 0; // reset sum
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      }
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      temp = temp.next;
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    }
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    /*---------------------------------------------------------------*/
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    return newHead.next; // skip dummy node which is created initially
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  }
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}