Sword To Offer 025 - 复杂链表的复制

/*
struct RandomListNode {
    int label;
    struct RandomListNode *next, *random;
    RandomListNode(int x) :
            label(x), next(NULL), random(NULL) {
    }
};
*/
class Solution {
public:
    RandomListNode* Clone(RandomListNode* pHead) {
        if(pHead == nullptr) {
            return nullptr;
        }
        for(RandomListNode* now = pHead; now != nullptr; now = now->next) {
            auto newNode = new RandomListNode(now->label);
            newNode->next = now->random;
            now->random = newNode;
        }
        for(RandomListNode* now = pHead; now != nullptr; now = now->next) {
            auto newNode = now->random;
            newNode->random = newNode->next != nullptr ? newNode->next->random : nullptr;
        }
        auto newHead = pHead->random;
        for(RandomListNode* now = pHead; now != nullptr; now = now->next) {
            auto newNode = now->random;
            now->random = newNode->next;
            newNode->next = now->next != nullptr ? now->next->random : nullptr;
        }
        return newHead;
    }
};