Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.
Example:
Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4
详见:https://leetcode.com/problems/merge-two-sorted-lists/description/
Java实现:
非递归:
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ class Solution { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { if(l1==null){ return l2; } if(l2==null){ return l1; } if(l1==null&&l2==null){ return null; } ListNode head=new ListNode(-1); ListNode cur=head; while(l1!=null&&l2!=null){ if(l1.val<l2.val){ cur.next=l1; l1=l1.next; }else{ cur.next=l2; l2=l2.next; } cur=cur.next; } cur.next=l1==null?l2:l1; return head.next; } }
递归:
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ class Solution { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { if(l1==null&&l2==null){ return null; } if(l1==null){ return l2; } if(l2==null){ return l1; } ListNode head=null; if(l1.val<l2.val){ head=l1; head.next=mergeTwoLists(l1.next,l2); }else{ head=l2; head.next=mergeTwoLists(l1,l2.next); } return head; } }