Sort a linked list using insertion sort.
A graphical example of insertion sort. The partial sorted list (black) initially contains only the first element in the list.
With each iteration one element (red) is removed from the input data and inserted in-place into the sorted list
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
# Definition for singly-linked list.
class ListNode:
def __init__(self, x):
self.val = x
self.next = None
class Solution:
def insertionSortList(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
if head is None or head.next is None:
return head
pre = ListNode(0)
res = pre
while head:
pre = res
while pre.next and pre.next.val<head.val:
pre = pre.next
temp = head.next
head.next = pre.next
pre.next = head
head = temp
return res.next