Merge Two Sorted Lists.py

# Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution:
    # @param two ListNodes
    # @return a ListNode
    def mergeTwoLists(self, l1, l2):
        if l1 is None:
            return l2
        if l2 is None:
            return l1
        if l1.val < l2.val:
            head = l1
            l1 = l1.next
        else:
            head = l2
            l2 = l2.next
        current = head
        while l1 and l2:
            if l1.val < l2.val:
                current.next = l1
                l1 = l1.next
            else:
                current.next = l2
                l2 = l2.next
            current = current.next
        if l1:
            current.next = l1
        else:
            current.next = l2
        return head

p1 = ListNode(1)
p2 = ListNode(2)
p3 = ListNode(3)
p4 = ListNode(4)
p5 = ListNode(5)
p6 = ListNode(6)
p1.next = p3
p3.next = p5
p2.next = p4
p4.next = p6

result = Solution()
ans = result.mergeTwoLists(p1, p2)
while ans:
    print ans.val
    ans = ans.next