class Node:
    def __init__(self, initdata):
        self.data = initdata  # 數(shù)據(jù)元素
        self.next = None      # 指向下一節(jié)點的引用
    def getData(self):
        return self.data
    def getNext(self):
        return self.next
    def setData(self, newdata):
        self.data = newdata
    def setNext(self, newnext):
        self.next = newnext

class LinkList:
    def __init__(self):
        self.head = None

class LinkList:
    def isEmpty(self):
        return self.head == None

class LinkList:
    def add(self, item):
        temp = Node(item)
        temp.setNext(self.head)
        self.head = temp

class LinkList:
    def length(self):
        current = self.head
        count = 0
        while current != None:
            count = count + 1
            current = current.getNext()
        return count

class LinkList:
    def search(self, item):
        current = self.head
        found = False
        while current != None and not found:
            if current.getData() == item:
                found = True
            else:
                current = current.getNext()
        return found

class LinkList:
    def remove(self, item):
        current = self.head
        previous = None
        found = False
        while not found:
            if current.getData() == item:
                found = True
            else:
                previous = current
                current = current.getNext()
                if current == None:
                	return found
        if previous == None:
            self.head = current.getnext()
        else:
            previous.setNext(current.getNext())

# 構(gòu)造節(jié)點
class Node:
    def __init__(self, initdata):
        self.data = initdata      # 數(shù)據(jù)元素
        self.next = None          # 指向下一節(jié)點的引用（python變量賦值的本質(zhì)是引用）
    def getData(self):            # 獲取節(jié)點的數(shù)據(jù)元素值
        return self.data
    def getNext(self):            # 獲取下一節(jié)點的引用 若有節(jié)點則直接視作為下一節(jié)點
        return self.next
    def setData(self, newdata):   # 給節(jié)點的數(shù)據(jù)元素設置值
        self.data = newdata
    def setNext(self, newnext):   # 給節(jié)點設置對下一節(jié)點的引用
        self.next = newnext

# 構(gòu)造鏈表
class LinkList:
    def __init__(self):            # 設置鏈表的頭部指向 無節(jié)點時為None 
        self.head = None
    def isEmpty(self):             # 判斷鏈表是否為空（是否有節(jié)點）
        return self.head == None
    def add(self, item):           # 給鏈表增加新節(jié)點（從鏈表頭位置增加）
        temp = Node(item)            # 創(chuàng)建節(jié)點并對新節(jié)點數(shù)據(jù)元素賦值
        temp.setNext(self.head)      # 新節(jié)點指向當前鏈表中的第一個節(jié)點
        self.head = temp             # 鏈表頭指向新節(jié)點
    def length(self):               # 計算鏈表長度（節(jié)點個數(shù)）
        current = self.head           # 引入current作為指向標識 指向第一個節(jié)點 或者None
        count = 0                     # 引入count作為計數(shù)變量
        while current != None:        # 當指向標識指向的不是鏈表末尾的None時
            count = count + 1           # 節(jié)點計數(shù)加一
            current = current.getNext() # 指向標識向后移動
        return count
    def search(self, item):                   # 搜索鏈表中節(jié)點
        current = self.head                     # 引入current作為指向標識 指向第一個節(jié)點
        found = False                           # 引入found作為尋找狀態(tài)標識
        while current != None and not found:    # 當current沒有指向None 并且 未找到節(jié)點
            if current.getData() == item:         # 如果current當前指向的節(jié)點是尋找的節(jié)點
                found = True                        # 找到
            else:                                 # 否則
                current = current.getNext()         # 指向標識向后移動 
        return found
    def remove(self, item):                 # 從鏈表中移除節(jié)點
        current = self.head                   # 引入current指向標識指向第一個節(jié)點
        previous = None                       # 引入previous指向標識指向current的上一個節(jié)點 所以當current指向第一個節(jié)點時 previous初始化指向的是None
        found = False                         # 引入尋找狀態(tài)標識 尋找需要移除的節(jié)點
        while not found:                      # 遍歷節(jié)點 以找到為循環(huán)結(jié)束條件
            if current.getData() == item:       # 如果當前節(jié)點是目標節(jié)點
                found = True                      # 找到
            else:                               # 當前節(jié)點不是目標節(jié)點
                previous = current                # previous指向當前節(jié)點
                current = current.getNext()       # current指向移動到下一個節(jié)點
                if current == None:               # 如果到最后都沒找到目標節(jié)點
                    return found	 
                                              # 搜索過程結(jié)束
        if previous == None:                  # 如果previous目前指向的是None 代表current指向的是鏈表的第一個節(jié)點 也就是說刪除的目標節(jié)點就是第一個節(jié)點
            self.head = current.getnext()        # 鏈表頭直接指向None表示刪除第一個節(jié)點
        else:                                 # 其他情況下
            previous.setNext(current.getNext())  #  當前節(jié)點的上一個節(jié)點指向當前節(jié)點的下一個節(jié)點

class Node:
    def __init__(self, initdata):
        self.data = initdata
        self.next = None
    def getData(self):
        return self.data
    def getNext(self):
        return self.next
    def setData(self, newdata):
        self.data = newdata
    def setNext(self, newnext):
        self.next = newnext

class LinkList:
    def __init__(self):
        self.head = None
    def isEmpty(self):
        return self.head == None
    def add(self, item):
        temp = Node(item)
        temp.setNext(self.head)
        self.head = temp
    def length(self):
        current = self.head
        count = 0
        while current != None:
            count = count + 1
            current = current.getNext()
        return count
    def search(self, item):
        current = self.head
        found = False
        while current != None and not found:
            if current.getData() == item:
                found = True
            else:
                current = current.getNext()
        return found
    def remove(self, item):
        current = self.head
        previous = None
        found = False
        while not found:
            if current.getData() == item:
                found = True
            else:
                previous = current
                current = current.getNext()
				if current == None:
					return found
        if previous == None:
            self.head = current.getnext()
        else:
            previous.setNext(current.getNext())