问题描述 链接到标题

1669.合并两个链表

解题思路 链接到标题

模拟

代码 链接到标题 

class Solution {
  public:
    ListNode *mergeInBetween(ListNode *list1, int a, int b, ListNode *list2) {
        ListNode *head = list1;
        ListNode *tail2 = list2;
        ListNode *head2 = list1;
        for (int i = 0; i < a - 1; i++) {
            head = head->next;
        }
        for (int i = 0; i < b; i++) {
            head2 = head2->next;
        }
        while (tail2->next != nullptr)
            tail2 = tail2->next;
        tail2->next = head2->next;
        head2->next = nullptr;
        head->next = list2;
        return list1;
    }
};