链表之单向链表

链表中最简单的一种是单向链表，它包含两个域，一个信息域和一个指针域。这个链接指向列表中的下一个节点，而最后一个节点则指向一个空值。

python代码实现：

# 链表中的节点的数据结构
class ListNode(object):
    def __init__(self, x): self.val = x self.next = None

# 实例化
A = ListNode('a')
B = ListNode('b') C = ListNode('c') A.next = B B.next = C # 这样，一条链表就形成了。 # 'a' -> 'b' -> 'c'

# 遍历链表
tmp = A
while tmp != None: print(tmp.val) tmp = tmp.next # 递归遍历链表 def listorder(head): if head: print(head.val) listorder(head.next) listorder(A)

翻转一条单向链表：

需求：

Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

class ListNode(object):
    def __init__(self, x): self.val = x self.next = None class Solution(object): def reverseList(self, head): """  :type head: ListNode  :rtype: ListNode  """ dummy = head tmp = dummy while head and head.next != None: dummy = head.next head.next = dummy.next dummy.next = tmp tmp = dummy return dummy head = ListNode(1) head.next = ListNode(2) head.next.next = ListNode(3) head.next.next.next = ListNode(4) head.next.next.next.next = ListNode(5) solution = Solution() reverse_head = solution.reverseList(head) tmp = reverse_head while tmp: print(tmp.val) tmp = tmp.next