class LNode:
? ? def __init__(self, elem):
? ? ? ? self.elem = elem
? ? ? ? self.pnext = None
?
def reverse(head):
? ? if head is None or head.pnext is None: #如果輸入的鏈表是空或者只有一個(gè)結(jié)點(diǎn)，直接返回當(dāng)前結(jié)點(diǎn)
? ? ? ? return head
? ? pre = None #用來(lái)指向上一個(gè)結(jié)點(diǎn)
? ? cur = newhead = head #cur是當(dāng)前的結(jié)點(diǎn)。newhead指向當(dāng)前新的頭結(jié)點(diǎn)
? ? while cur:
? ? ? ? newhead = cur
? ? ? ? temp = cur.pnext
? ? ? ? cur.pnext = pre #將當(dāng)前的結(jié)點(diǎn)的指針指向前一個(gè)結(jié)點(diǎn)
? ? ? ? pre = cur
? ? ? ? cur = temp
? ? return newhead
?
if __name__=="__main__":
? ? head = LNode(1)
? ? p1 = LNode(2)
? ? p2 = LNode(3)
? ? head.pnext = p1
? ? p1.pnext = p2
? ? p = reverse(head)
? ? while p:
? ? ? ? print(p.elem)
? ? ? ? p = p.pnext

class LNode:
? ? def __init__(self, elem):
? ? ? ? self.elem = elem
? ? ? ? self.pnext = None
?
def reverse(head):
? ? if not head or not head.pnext:
? ? ? ? return head
? ? else:
? ? ? ? newhead = reverse(head.pnext)
? ? ? ? head.pnext.pnext = head #令下一個(gè)結(jié)點(diǎn)的指針指向當(dāng)前結(jié)點(diǎn)
? ? ? ? head.pnext = None #斷開(kāi)當(dāng)前結(jié)點(diǎn)與下一個(gè)結(jié)點(diǎn)之間的指針指向聯(lián)系，令其指向空
? ? ? ? return newhead
?
?
if __name__=="__main__":
? ? head = LNode(1)
? ? p1 = LNode(2)
? ? p2 = LNode(3)
? ? head.pnext = p1
? ? p1.pnext = p2
? ? p = reverse(head)
? ? while p:
? ? ? ? print(p.elem)
? ? ? ? p = p.pnext