leetcode之328. Odd Even Linked List（C++解法）

题目：
Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.

You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.

Example:
Given 1->2->3->4->5->NULL,
return 1->3->5->2->4->NULL.

Note:
The relative order inside both the even and odd groups should remain as it was in the input.
The first node is considered odd, the second node even and so on …
*************************我是分割线****************************

/** * 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) {        if(!head || !head->next) return head;        ListNode *odd=head;        ListNode *even=head->next;        ListNode *po=head;        ListNode *pe=head->next;        ListNode *p=head->next->next;        int i=3;        while(p)        {            if(1==i%2)            {                //odd                odd->next=p;                odd=odd->next;            }            else            {                //even                even->next=p;                even=even->next;            }            i++;            p=p->next;        }        even->next=nullptr;        odd->next=pe;        return po;    }};

测试程序就是在上一篇上面加了一个函数哈~~~