[数据结构]奇偶链表（leetcode328）c++

奇偶链表（leetcode328）c++

https://leetcode-cn.com/problems/odd-even-linked-list/

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* oddEvenList(ListNode* head) {
        //将奇节点放在一个链表里，偶链表放在另一个链表里。然后把偶链表接在奇链表的尾部
        if(head==nullptr){
            return head;
        }
        ListNode *old_head=head;
        ListNode *p=head->next;
        ListNode *new_head=p;

        while(p && p->next){
            old_head->next=p->next;
            old_head=old_head->next;
            p->next=old_head->next;
            p=p->next;
        }
        old_head->next=new_head;
        return head;

    }
};