题目
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.
翻译
合并两个有序的链表
Hints
Related Topics: LinkedList
参考 归并排序-维基百科,可以递归也可以迭代,基本的链表操作
代码
Java
/**
* 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.val<l2.val){
l1.next = mergeTwoLists(l1.next,l2);
return l1;
}else{
l2.next = mergeTwoLists(l1,l2.next);
return l2;
}
}
}
Python
//recursively
class Solution(object):
def mergeTwoLists(self, l1, l2):
if l1==None: return l2;
if l2==None: return l1;
if l1.val<l2.val:
l1.next = self.mergeTwoLists(l1.next,l2)
return l1
else:
l2.next = self.mergeTwoLists(l1,l2.next)
return l2
//iteratively
class Solution(object):
def mergeTwoLists(self, l1, l2):
dummy = curr = ListNode(0)
while l1 and l2:
if l1.val<l2.val:
curr.next = l1
l1 = l1.next
else:
curr.next = l2
l2 = l2.next
curr = curr.next
curr.next = l1 or l2
return dummy.next