[Link] https://leetcode.com/problems/merge-two-sorted-lists/
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/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
ListNode nullNode = new ListNode();
ListNode curNode = nullNode;
ListNode node1 = list1, node2 = list2;
while(node1 != null && node2 != null) {
if(node1.val < node2.val) {
curNode.next = node1;
curNode = node1;
node1 = node1.next;
if(node1 == null) break;
} else {
curNode.next = node2;
curNode = node2;
node2 = node2.next;
if(node2 == null) break;
}
}
if(node1 == null && node2 != null) curNode.next = node2;
else if(node1 != null && node2 == null) curNode.next = node1;
return nullNode.next;
}
}