[LeetCode] Copy List with Random Pointer

最新推荐文章于 2019-10-21 22:50:54 发布

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最新推荐文章于 2019-10-21 22:50:54 发布

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分类专栏： LeetCode

本文链接：https://blog.youkuaiyun.com/jinyonghorse/article/details/12906629

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本文介绍了一种克隆包含随机指针的单链表的方法，使用映射保存原链表中的节点映射关系，确保了链表结构和随机指针的正确复制。

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.

该题与clone graph类似，使用一个map保存原链表中的映射

/**
 * Definition for singly-linked list with a random pointer.
 * struct RandomListNode {
 *     int label;
 *     RandomListNode *next, *random;
 *     RandomListNode(int x) : label(x), next(NULL), random(NULL) {}
 * };
 */
class Solution {
public:
    RandomListNode *copyRandomList(RandomListNode *head) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(head == NULL) return NULL;
        map<int,RandomListNode *> nodeMap;
        set<int> visited;
        vector<RandomListNode *> currentLevel, nextLevel;
        nodeMap[head->label] = new RandomListNode(head->label);
        currentLevel.push_back(head);
        while(currentLevel.size() > 0) {
            nextLevel.clear();
            for(int i = 0; i < currentLevel.size(); i++) {
                RandomListNode *one = currentLevel[i];
                if(nodeMap.find(one->label) == nodeMap.end()) {
                    nodeMap[one->label] = new RandomListNode(one->label);
                }
                visited.insert(one->label);
                RandomListNode *tmp = nodeMap[one->label];
                RandomListNode *next = one->next;
                RandomListNode *ran = one->random;
                if(next == NULL) {
                    tmp->next = NULL;
                }else {
                    if(nodeMap.find(next->label) == nodeMap.end()) {
                        nodeMap[next->label] = new RandomListNode(next->label);
                     }
                     tmp->next = nodeMap[next->label];
                     if(visited.count(next->label) == 0) {
                         visited.insert(next->label);
                         nextLevel.push_back(next);
                     }
                }
                
                if(ran == NULL) {
                    tmp->random = NULL;
                }else {
                    if(nodeMap.find(ran->label) == nodeMap.end()) {
                        nodeMap[ran->label] = new RandomListNode(ran->label);
                    }
                    tmp->random = nodeMap[ran->label];
                    if(visited.count(ran->label) == 0) {
                        visited.insert(ran->label);
                        nextLevel.push_back(ran);
                    }
                }
            }
            currentLevel.clear();
            currentLevel.assign(nextLevel.begin(),nextLevel.end());
        }
        return nodeMap[head->label];
    }
};