21. Merge Two Sorted Lists
题目 21. Merge Two Sorted Lists
思路分析
类似于归并排序
代码实现
/**
* 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 head = new ListNode(-1);
ListNode tail = head;
while(list1!=null && list2!=null){
if(list1.val <= list2.val){
tail.next = list1;
list1=list1.next;
}else{
tail.next = list2;
list2=list2.next;
}
tail=tail.next;
}
if(list1!=null){
tail.next=list1;
}else{
tail.next=list2;
}
return head.next;
}
}
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