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package LeetCode_138 /** * 138. Copy List with Random Pointer * https://leetcode.com/problems/copy-list-with-random-pointer/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 representing Node.val random_index: the index of the node (range from 0 to n-1) where random pointer points to, or null if it does not point to any node. * */ class Node(var `val`: Int) var next: Node? = null var random: Node? = null class Solution /* * solution 1:HashMap, Time complexity:O(n), Space complexity:O(n) * */ fun copyRandomList(node: Node?): Node? val map = HashMap<Node, Node>() //handle node copy var cur = node while (cur != null) map.put(cur, Node(cur.`val`)) cur = cur.next //handler node‘s next and random var curNode = node while (curNode != null) if (curNode.next!=null) map.get(curNode)?.next = map.get(curNode.next!!) if (curNode.random!=null) map.get(curNode)?.random = map.get(curNode.random!!) curNode = curNode.next return map.get(node!!)