LeetCode 138. Copy List with Random Pointer

思路

《剑指Offer》#26
基本步骤是：

1. 在每个节点后面，拷贝一个相同的节点：A->A’->B->B’…
2. 拷贝随机节点，即A’->random是A->random->next
3. 分离拷贝后的链表

代码

（脑抽了一下，break和continue打错，看了半天）

/**
 * 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:
    void makeNodeDup(RandomListNode* head){
        //make copy of linked node
        while(head!=NULL){
            RandomListNode* replica = new RandomListNode(head->label);
            replica->next = head->next;
            head->next = replica;
            head = replica->next;
        }
    }
    void copyRandomLink(RandomListNode* head){
        //copy random link in new-generated replicas
        while(head != NULL){
            if(head->random == NULL){
                head = head->next->next;
                continue;
            }
            RandomListNode* replica = head->next;
            replica->random = head->random->next;
            head = replica->next;
        }
    }
    RandomListNode* detachReplica(RandomListNode* head){
        RandomListNode* replicaHead = NULL;
        while(head != NULL){
            RandomListNode* replica = head->next;
            if(replicaHead == NULL){
                replicaHead = replica;
            }
            head->next = replica->next;
            if(replica->next != NULL){
                replica->next = replica->next->next;
            } else {
                replica->next = NULL;
            }
            head = head->next;
        }
        return replicaHead;
    }
    RandomListNode *copyRandomList(RandomListNode *head) {
        makeNodeDup(head);
        copyRandomLink(head);
        return detachReplica(head);
    }
};