你需要分配

l1

和

l2

tempNode.val

L1

节点本身到

tempNode

# Definition for singly-linked list.

class ListNode:

def __init__(self, x=None):

self.val = x

self.next = None

a = ListNode(5)

b = ListNode(10)

c = ListNode(20)

e = ListNode(0)

f = ListNode(5)

g = ListNode(21)

h = ListNode(30)

a.next = b

b.next = c

e.next = f

f.next = g

g.next = h

class Solution:

def mergeTwoLists(self, l1, l2):

returnNode = tempNode = ListNode()

while l1 or l2:

if not l1:

print('l1 is empty; adding value from l2:', l2.val)

tempNode.val = l2.val

tempNode.next = ListNode()

tempNode = tempNode.next

l2 = l2.next

elif not l2:

print('l2 is empty; adding value from l1:', l1.val)

tempNode.val = l1.val

tempNode.next = ListNode()

tempNode = tempNode.next

l1 = l1.next

elif l1.val < l2.val:

print("l1.val < l2.val", l1.val, l2.val)

tempNode.val = l1.val

tempNode.next = ListNode()

tempNode = tempNode.next

l1 = l1.next

elif l1.val == l2.val:

print("l1.val == l2.val", l1.val, l2.val)

#If both the values are equal, assign l1's value first

#then make l2's value follow l1's value using tempNode

tempNode.val = l1.val

tempNode.next = ListNode() #Because of the previous statement, after execution of this statement, I'm assuming tempNode.val is now l1.val and tempNode.next = l1.next

tempNode = tempNode.next

#tempNode.next is supposed to be equal to l1.next, instead assign it to l2

tempNode.val = l2.val

tempNode.next = ListNode() #Because of the previous statement, after execution of this statement, I'm assuming tempNode.val is now l2.val and tempNode.next = l2.next

tempNode = tempNode.next

#Increment both l1 and l2

l1 = l1.next

l2 = l2.next

else:

print("l1.val > l2.val", l1.val, l2.val)

tempNode.val = l2.val

tempNode.next = ListNode()

tempNode = tempNode.next

l2 = l2.next

return returnNode

sol = Solution()

node = sol.mergeTwoLists(a, e)

while node and node.val is not None:

print(node.val)

node = node.next

l1.val > l2.val 5 0

l1.val == l2.val 5 5

l1.val < l2.val 10 21

l1.val < l2.val 20 21

l1 is empty; adding value from l2: 21

l1 is empty; adding value from l2: 30

0

5

5

10

20

21

30