[LeetCode OJ] Reorder List—Given a singly linked list L: L0→L1→…→Ln-1→Ln, reorder it to: L0→Ln→L1→Ln-
For example,Given {1,2,3,4}, reorder it to {1,4,2,3}.
1 /**
2 * Definition for singly-linked list.
3 * struct ListNode {
4 * int val;
5 * ListNode *next;
6 * Li