Given a list, each node contains a random additional pointer that can point to any node in the linked list node or empty.
The requirement to return a deep copy of the list.
We use a linked list of n nodes to the input / output in a linked list. Each node with a [val, random_index] represents:
val: a Node.val integer representation.
random_index: random pointer node index (ranging from 0 to n-1); if you do not point to any node, was null.
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:
输入：head = [[1,1],[2,1]]
输出：[[1,1],[2,1]]
示例 3：输入：head = [[3,null],[3,0],[3,null]]
输出：[[3,null],[3,0],[3,null]]
示例 4：
输入：head = []
输出：[]
解释：给定的链表为空（空指针），因此返回 null。Source: stay button (LeetCode)
link: https: //leetcode-cn.com/problems/copy-list-with-random-pointer
"""
# 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
deep_dict = {} #用字典存新旧节点
old = head
new = Node(0)
while(head):
key = head
new.next = Node(head.val) #新节点
value = new.next
new = new.next
deep_dict.update({key:value}) #新旧节点存进字典
head = head.next
for key,value in deep_dict.items():
if key.random:
# 例value: a' ,key: a ,a.random = c,deep_dict[a.random]=c',所以a'.random = c'
value.random = deep_dict[key.random]
return deep_dict[old]
