328.奇偶链表

下面是题目

下面是题目给出的模板

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* oddEvenList(ListNode* head) {

    }
};

看了几种方法，都大同小异，无非是代码量的区别，这里给出一种简单易懂的代码

class Solution {
public:
    ListNode* oddEvenList(ListNode* head) {
        if(!head)
            return head;
        ListNode *even = head->next;
        ListNode *even_head = head->next;
        ListNode *odd = head;
        while(1)
        {
            if(even==NULL||even->next==NULL)
            {//遍历完成后，把odd和even的头节点连起来，再return head
                odd->next = even_head;
                return head;
            }
            //交错插入，形象的说法就是拉链算法
            odd->next = even->next;
            odd = odd->next;
            even->next = odd->next;
            even = even ->next;
        }
    }
};