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class Node(object): """节点""" def __init__(self, item): self.item = item self.next = None
class SinCycLinkedlist(object): """单向循环链表""" def __init__(self): self.__head = None
def is_empty(self): """判断链表是否为空""" return self.__head == None
def length(self): """返回链表的⻓度""" # 如果链表为空，返回⻓度0 if self.is_empty(): return 0 count = 1 cur = self.__head while cur.next != self.__head: count += 1 cur = cur.next return count
def travel(self): """遍历链表""" if self.is_empty(): return cur = self.__head print cur.item, while cur.next != self.__head: cur = cur.next print cur.item, print ""
def add(self, item): """头部添加节点""" node = Node(item) if self.is_empty(): self.__head = node node.next = self.__head else: #添加的节点指向_head node.next = self.__head # 移到链表尾部，将尾部节点的next指向node cur = self.__head while cur.next != self.__head: cur = cur.next cur.next = node #_head指向添加node的 self.__head = node
def append(self, item): """尾部添加节点""" node = Node(item) if self.is_empty(): self.__head = node node.next = self.__head else: # 移到链表尾部 cur = self.__head while cur.next != self.__head: cur = cur.next # 将尾节点指向node cur.next = node # 将node指向头节点_head node.next = self.__head
def insert(self, pos, item): """在指定位置添加节点""" if pos <= 0: self.add(item) elif pos > (self.length()-1): self.append(item) else: node = Node(item) cur = self.__head count = 0 # 移动到指定位置的前⼀个位置 while count < (pos-1): count += 1 cur = cur.next
node.next = cur.next cur.next = node
def remove(self, item): """删除⼀个节点""" # 若链表为空，则直接返回 if self.is_empty(): return # 将cur指向头节点 cur = self.__head pre = None while cur.next != self.__head: if cur.item == item: # 先判断此结点是否是头节点 if cur == self.__head: # 头节点的情况 # 找尾节点 rear = self.__head while rear.next != self.__head: rear = rear.next self.__head = cur.next rear.next = self.__head else: # 中间节点 pre.next = cur.next return else: pre = cur cur = cur.next # 退出循环，cur指向尾节点 if cur.item == item: if cur == self.__head: # 链表只有⼀个节点 self.__head = None else: # pre.next = cur.next pre.next = self.__head
def search(self, item): """查找节点是否存在""" if self.is_empty(): return False cur = self.__head if cur.item == item: return True while cur.next != self.__head: cur = cur.next if cur.item == item: return True return False
if __name__ == "__main__": ll = SinCycLinkedlist() ll.add(1) ll.add(2) ll.append(3) ll.insert(2, 4) ll.insert(4, 5) ll.insert(0, 6) print "length:",ll.length() ll.travel() print ll.search(3) print ll.search(7) ll.remove(1) print "length:",ll.length() ll.travel()
