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/**
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 * Definition for singly-linked list.
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 * public class ListNode {
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 *     int val;
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 *     ListNode next;
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 *     ListNode() {}
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 *     ListNode(int val) { this.val = val; }
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 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
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 * }
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 */
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class Solution {
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    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
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        ListNode newList = new ListNode();
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        ListNode curr = newList;
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        while(list1 != null && list2 != null) {
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            if(list1.val <= list2.val) {
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                curr.next = list1;
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                list1 = list1.next;
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            } else {
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                curr.next = list2;
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                list2 = list2.next;
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            }
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            curr = curr.next;
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        }
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        if(list1 == null) {
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            curr.next = list2;
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        }
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        if(list2 == null) {
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            curr.next = list1;
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        }
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        return newList.next;
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    }
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}