Leetcode (Python): Insertion Sort List

Sort a linked list using insertion sort.

Solution:

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

class Solution:
# @param head, a ListNode
# @return a ListNode
    def insertionSortList(self, head):
        if not head:
            return head
        dummy = ListNode(0)                       
        dummy.next = head
        lastSorted = head
        while lastSorted.next:
            if lastSorted.next.val < lastSorted.val:          
                tmp = dummy                       
                while tmp.next.val < lastSorted.next.val: 
                    tmp = tmp.next
                nextToSort = lastSorted.next                 
                lastSorted.next = nextToSort.next
                nextToSort.next = tmp.next
                tmp.next = nextToSort
            else:
                lastSorted = lastSorted.next
        return dummy.next