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Copy List with Random Pointer@LeetCode

LeetCode
Word count: 251 / Reading time: 1 min
2015/04/25 Share

Copy List with Random Pointer

节点中需要拷贝的两个引用是next和random。next引用比较好拷贝，相当直接复制普通列表。而对于random则需要目标节点已存在才比较容易些拷贝代码，采用的办法就是构造一个HashMap，其中key是原节点，value是拷贝节点，在拷贝random引用的过程中，直接用map.get(node.random)来获取相应的目标节点即可。

实现代码：

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/**
 * Definition for singly-linked list with a random pointer.
 * class RandomListNode {
 *     int label;
 *     RandomListNode next, random;
 *     RandomListNode(int x) { this.label = x; }
 * };
 */
public class Solution {
    public RandomListNode copyRandomList(RandomListNode head) {
        if (head == null)
            return null;
        RandomListNode targetNode = head, copyPreHead = new RandomListNode(-1), copyNode = copyPreHead;
        HashMap<RandomListNode, RandomListNode> copiedMap = new HashMap<RandomListNode, RandomListNode>();
        while (targetNode != null) {
            copyNode.next = new RandomListNode(targetNode.label);
            copiedMap.put(targetNode, copyNode.next);
            targetNode = targetNode.next;
            copyNode = copyNode.next;
        }
        targetNode = head;
        copyNode = copyPreHead.next;
        while (targetNode != null) {
            if (targetNode.random != null) {
                copyNode.random = copiedMap.get(targetNode.random);
            }
            targetNode = targetNode.next;
            copyNode = copyNode.next;
        }
        return copyPreHead.next;
    }
}

原文作者: findingsea

原文链接: http://findingsea.github.io/2015/04/25/copy-list-with-random-pointer-at-leetcode/

发表日期: April 25th 2015, 1:03:00 pm

版权声明: 本文采用知识共享署名-非商业性使用 4.0 国际许可协议进行许可

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