python單向迴圈連結串列
阿新 • • 發佈:2019-01-02
單向迴圈連結串列
單鏈表的一個變形是單向迴圈連結串列,連結串列中最後一個節點的next域不再為None,而是指向連結串列的頭節點。
操作
- is_empty() 判斷連結串列是否為空
- length() 返回連結串列的長度
- travel() 遍歷
- add(item) 在頭部新增一個節點
- append(item) 在尾部新增一個節點
- insert(pos, item) 在指定位置pos新增節點
- remove(item) 刪除一個節點
- search(item) 查詢節點是否存在
實現
class Node(object): """節點""" def __init__(self, item): self.item = item self.next = None class SinCycLinkedlist(object): """單向迴圈連結串列""" def __init__(self): self.__head = None def is_empty(self): """判斷連結串列是否為空""" return self.__head == None def length(self): """返回連結串列的長度""" # 如果連結串列為空,返回長度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): """遍歷連結串列""" 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): """頭部新增節點""" node = Node(item) if self.is_empty(): self.__head = node node.next = self.__head else: #新增的節點指向_head node.next = self.__head # 移到連結串列尾部,將尾部節點的next指向node cur = self.__head while cur.next != self.__head: cur = cur.next cur.next = node #_head指向新增node的 self.__head = node def append(self, item): """尾部新增節點""" node = Node(item) if self.is_empty(): self.__head = node node.next = self.__head else: # 移到連結串列尾部 cur = self.__head while cur.next != self.__head: cur = cur.next # 將尾節點指向node cur.next = node # 將node指向頭節點_head node.next = self.__head def insert(self, pos, item): """在指定位置新增節點""" if pos <= 0: self.add(item) elif pos > (self.length()-1): self.append(item) else: node = Node(item) cur = self.__head count = 0 # 移動到指定位置的前一個位置 while count < (pos-1): count += 1 cur = cur.next node.next = cur.next cur.next = node def remove(self, item): """刪除一個節點""" # 若連結串列為空,則直接返回 if self.is_empty(): return # 將cur指向頭節點 cur = self.__head pre = None while cur.next != self.__head: if cur.item == item: # 先判斷此結點是否是頭節點 if cur == self.__head: # 頭節點的情況 # 找尾節點 rear = self.__head while rear.next != self.__head: rear = rear.next self.__head = cur.next rear.next = self.__head else: # 中間節點 pre.next = cur.next return else: pre = cur cur = cur.next # 退出迴圈,cur指向尾節點 if cur.item == item: if cur == self.__head: # 連結串列只有一個節點 self.__head = None else: # pre.next = cur.next pre.next = self.__head def search(self, item): """查詢節點是否存在""" 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()