"""
86. Partition List
Difficulty: Medium
https://leetcode.com/problems/partition-list/

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Given the head of a linked list and a value x, partition it such that
all nodes less than x come before nodes greater than or equal to x.

You should preserve the original relative order of the nodes in each
of the two partitions.

 

Example 1:

Input: head = [1,4,3,2,5,2], x = 3
Output: [1,2,2,4,3,5]

Example 2:

Input: head = [2,1], x = 2
Output: [1,2]

 

Constraints:

	• The number of nodes in the list is in the range [0, 200].

	• -100 <= Node.val <= 100

	• -200 <= x <= 200
"""

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def partition(self, head: ListNode | None, x: int) -> ListNode | None: