算法练习(10) - 反转链表(O(n))

class Solution {
    public ListNode reverseList(ListNode head) {
	ListNode temp = null;
	ListNode res = null;
        while(head != null){
		// 3. 缓存结果指针
		temp = res;
		// 2. 缓存头删指针
		res = head;
		// 1. 头删
 		head = head.next;      		
		// 4. 头插
		res.next = temp;
	}
        return res;
    }
}