Insertion Sort List
Created: April 8, 2020 by [lek-tin]
Last updated: April 8, 2020
Algorithm of Insertion Sort
Insertion sort iterates, consuming one input element each repetition, and growing a sorted output list. At each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list, and inserts it there. It repeats until no input elements remain.
Example 1
Input: 4->2->1->3
Output: 1->2->3->4
Example 2
Input: -1->5->3->4->0
Output: -1->0->3->4->5
Solution
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def insertionSortList(self, head: ListNode) -> ListNode:
if not head: return head
dummy = ListNode(0)
curr = head
prev, curr_next = ListNode(0), ListNode(0)
while curr:
curr_next = curr.next
prev = dummy
while prev.next and prev.next.val < curr.val:
prev = prev.next
curr.next = prev.next
prev.next = curr
curr = curr_next
return dummy.next