每日一练——随机链表的复制

138. 随机链表的复制 - 力扣（LeetCode）

关键点：通过“相互插入”式的复制方法来把源链表和目标链表的random联系起来。 

/**
 * Definition for a Node.
 * struct Node {
 *     int val;
 *     struct Node *next;
 *     struct Node *random;
 * };
 */

typedef int LDataType;
typedef struct Node Node;
 
Node* BuyNode(LDataType x)
{
    Node* newnode = (Node*)malloc(sizeof(Node));
    if (NULL == newnode)
    {
        perror("malloc failed");
        exit(-1);
    }
    newnode->val = x;
    newnode->next = NULL;
    newnode->random = NULL;
    return newnode;
}


struct Node* copyRandomList(struct Node* head)
{
    if (NULL == head)
        return NULL;
    // 穿插复制
    struct Node* cur = head;
    while (cur)
    {
        struct Node* newnode = BuyNode(cur->val);
        newnode->next = cur->next;
        cur->next = newnode;
        cur = newnode->next;
    }
    // 处理random
    cur = head;
    while (cur)
    {
        if (cur->random)
            cur->next->random = cur->random->next;
        cur = cur->next->next;
    }
    // 拆开
    cur = head;
    struct Node* copyhead = head->next;
    struct Node* copy = copyhead;
    while (1)
    {
        cur->next = copy->next;
        cur = cur->next;
        if (NULL == cur)
        {
            copy->next = NULL;
            break;
        }
        copy->next = cur->next;
        copy = copy->next;
    }
    return copyhead;
}