A linked list of length n
is given such that each node contains an additional random pointer, which could point to any node in the list, or null
.
Construct a deep copy of the list. The deep copy should consist of exactly n
brand new nodes, where each new node has its value set to the value of its corresponding original node. Both the next
and random
pointer of the new nodes should point to new nodes in the copied list such that the pointers in the original list and copied list represent the same list state. None of the pointers in the new list should point to nodes in the original list.
For example, if there are two nodes X
and Y
in the original list, where X.random --> Y
, then for the corresponding two nodes x
and y
in the copied list, x.random --> y
.
Return the head of the copied linked 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
) that therandom
pointer points to, ornull
if it does not point to any node.
Your code will only be given the head
of the original linked list.
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]]
Constraints:
-
0 <= n <= 1000
-
-104 <= Node.val <= 104
-
Node.random
isnull
or is pointing to some node in the linked list.
SOLUTION:
"""
# 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 copy(self, head):
newhead = None
if head:
newhead = self.visited.get(head, Node(head.val))
self.visited[head] = newhead
if head.random != None:
newhead.random = self.visited.get(head.random, Node(head.random.val))
self.visited[head.random] = newhead.random
newhead.next = self.copy(head.next)
return newhead
def copyRandomList(self, head: 'Optional[Node]') -> 'Optional[Node]':
self.visited = {}
return self.copy(head)
Top comments (0)