Description
A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.
Return a deep copy of the list.
The Linked List is represented in the input/output as a list of n
nodes. Each node is represented as a pair of [val, random_index]
where:
val
: an integer representingNode.val
random_index
: the index of the node (range from0
ton-1
) where random pointer points to, ornull
if it does not point to any node.
Example 1:
Input: head = [[7,null],[13,0],[11,4],[10,2],[1,0]]
Output: [[7,null],[13,0],[11,4],[10,2],[1,0]]
Example 2:
Input: head = [[1,1],[2,1]]
Output: [[1,1],[2,1]]
Example 3:
Input: head = [[3,null],[3,0],[3,null]]
Output: [[3,null],[3,0],[3,null]]
Example 4:
Input: head = []
Output: []
Explanation: Given linked list is empty (null pointer), so return null.
Constraints:
-10000 <= Node.val <= 10000
Node.random
is null or pointing to a node in the linked list.- Number of Nodes will not exceed 1000.
Solutions
1. Copy same
# Time: O(n)
# Space: O(1)
"""
# Definition for a Node.
class Node:
def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
self.val = int(x)
self.next = next
self.random = random
"""
class Solution:
def copyRandomList(self, head: 'Node') -> 'Node':
if not head:
return
# copy nodes
cur = head
while cur:
nxt = cur.next
cur.next = Node(cur.val, cur.next, cur.random)
cur.next.next = nxt
cur = nxt
# copy random pointers
cur = head
while cur:
if cur.random:
cur.next.random = cur.random.next
cur = cur.next.next
# separate two parts
second = cur = head.next
while cur.next:
head.next = cur.next
head = head.next
cur.next = head.next
cur = cur.next
head.next = None
return second
# 18/18 cases passed (48 ms)
# Your runtime beats 39.22 % of python3 submissions
# Your memory usage beats 100 % of python3 submissions (13.3 MB)