206 reverse linked list

206. 反转链表

go：

双指针法：

/**

 * Definition for singly-linked list.

 * type ListNode struct {

 *     Val int

 *     Next *ListNode

 * }
 */
func reverseList(head *ListNode) *ListNode {
    cur := head
    var pre *ListNode

    for cur != nil {
        temp := cur.Next
        cur.Next = pre
        pre = cur
        cur = temp
    }

    return pre
}