python-leetcode-分隔链表

86. 分隔链表 - 力扣（LeetCode）

# 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: Optional[ListNode], x: int) -> Optional[ListNode]:
        # 创建两个虚拟头节点
        smaller_head = ListNode(0)
        greater_head = ListNode(0)
        
        # 初始化两个指针
        smaller = smaller_head
        greater = greater_head
        
        # 遍历链表
        while head:
            if head.val < x:
                # 将节点加入到小于 x 的链表中
                smaller.next = head
                smaller = smaller.next
            else:
                # 将节点加入到大于等于 x 的链表中
                greater.next = head
                greater = greater.next
            head = head.next
        
        # 断开大于等于 x 链表的末尾
        greater.next = None
        
        # 连接两个链表
        smaller.next = greater_head.next
        
        return smaller_head.next