翻转链表的三种方法（python实现）

具体方法来自看图理解单链表的反转，以下为该博客中方法的python实现以及测试

方法一：利用三个指针逐个翻转

def func1(head):    p = head    q = head.next    p.next = None    while q:        r = q.next        q.next = p        p = q        q = r    return p 

方法二：尾插法翻转

def func2(head):    p = head.next    while p.next:        q = p.next        p.next = q.next        head.next = q        q.next = p    p.next = head    head = head.next    p.next.next = None    return head

方法三：递归

def func3(head):    if head.next == None:        return head    new_head = func3(head.next)    head.next.next = head    head.next = None    return new_head

节点定义及测试用例：

#节点定义class LNode:    def __init__(self, x):        self.val = x        self.next = None#测试用例if __name__ == '__main__':    l1 = LNode(3)    l1.next = LNode(2)    l1.next.next = LNode(1)    l1.next.next.next = LNode(99)    l = func3(l1)    print l.val, l.next.val, l.next.next.val, l.next.next.next.val