Convert Binary Number in a Linked List to Integer 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 int getDecimalValue(ListNode head) {
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    head = reverse(head);
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    int ans = 0;
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    int pow = 0;
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    ListNode temp = head;
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    while (temp != null) {
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      ans = ans + temp.val * (int) Math.pow(2, pow++);
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      temp = temp.next;
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    }
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    return ans;
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  }
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  public ListNode reverse(ListNode head) {
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    ListNode prev = null;
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    ListNode pres = head;
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    ListNode Next = pres.next;
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    while (pres != null) {
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      pres.next = prev;
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      prev = pres;
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      pres = Next;
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      if (Next != null) {
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        Next = Next.next;
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      }
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    }
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    head = prev;
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    return head;
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  }
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}