[数据结构与算法]算法-链表

#节点
class Node(object):
    def __init__(self, elem):
        self.elem = elem
        self.next = None

#单向链表
class SingleLinkList(object):
    #初始化的时候要传节点，不然就默认空，头指向空
    def __init__(self, node = None):
        self.__head = node

    #链表是否为空
    def is_empty(self):
        return self.__head == None

    #链表长度
    def length(self):
        #游标
        cur = self.__head
        res = 0
        while cur != None:
            res += 1
            cur = cur.next
        return res

    #遍历整个链表
    def travel(self):
        cur = self.__head
        while cur != None:
            print(cur.elem)
            cur = cur.next
        print ("")

    #链表头部添加元素
    def add(self, item):
        node = Node(item)
        node.next = self.__head
        self.__head = node

    #链表尾部添加元素
    def append(self, item):
        cur = self.__head
        node = Node(item)
        if self.is_empty():
            self.__head = node
        else:
            while cur.next != None:
                cur = cur.next
            cur.next = node

    #指定位置添加元素
    def insert(self, pos, item):
        if pos <= 0:
            self.add(item)
            return
        elif pos >= self.length():
            self.append(item)
            return
        #pos 从0开始
        per = self.__head
        node = Node(item)
        i = 0
        while i < pos - 1:
            per = per.next
            i += 1
        node.next = per.next
        per.next = node



    #删除节点
    def remove(self, item):
        #通过双指针的运用，比较方便的删除节点，代码也好理解。
        cur = self.__head
        per = None
        if cur == None:
            return

        while cur != None:
            if cur.elem == item:
                if cur == self.__head:
                    self.__head = cur.next
                else:
                    per.next = cur.next
                break
            else:
                per = cur
                cur = cur.next

        per = self.__head
        if per == None:
            return
        elif per.elem == item:
            per = per.next
            return
        while per.next != None:
            if per.next.elem == item:
                per.next.next = per.next
                return
            per = per.next

    #查找节点是否存在
    def search(self, item):
        cur = self.__head
        count = 0
        while count < self.length():
            count += 1
            if cur.elem == item:
                return True
        return False

    # 查找节点是否存在
    def search1(self, item):
        cur = self.__head
        while cur != None:
            if cur.elem == item:
                return True
            else:
                cur = cur.next
        return False


if __name__ == "__main__":
    ll = SingleLinkList()
    print("length:", ll.length())
    ll.append(3)
    print ("length:",ll.length())
    ll.append(2)
    ll.append(1)
    ll.travel()

    ll.add(4)
    ll.travel()

    ll.insert(-1, 6)
    ll.travel()

    ll.insert(1, 5)
    ll.travel()

    ll.insert(10, 0)
    ll.travel()

    ll.remove(6)
    ll.travel()

    ll.remove(4)
    ll.travel()

    ll.remove(0)
    ll.travel()

    ll.remove(100)
    ll.travel()

    for i  in range(0, 2000):
        ll.append(i)

    import time
    a = time.time()
    ll.search(10000)
    print("length " + str(time.time() - a))

    b = time.time()
    ll.search1(10000)
    print("no length " + str(time.time() - b))

?

?

#节点
class Node(object):
    def __init__(self, elem):
        self.elem = elem
        self.next = None
        self.prev = None

#单向链表
class DoubleLinkList(object):
    #初始化的时候要传节点，不然就默认空，头指向空
    def __init__(self, node = None):
        self.__head = node

    #链表是否为空
    def is_empty(self):
        return self.__head == None

    #链表长度
    def length(self):
        #游标
        cur = self.__head
        res = 0
        while cur != None:
            res += 1
            cur = cur.next
        return res

    #遍历整个链表
    def travel(self):
        cur = self.__head
        while cur != None:
            print(cur.elem)
            cur = cur.next
        print ("")

    #链表头部添加元素
    def add(self, item):
        node = Node(item)
        node.next = self.__head
        self.__head = node
        node.next.prev = node

    #链表尾部添加元素
    def append(self, item):
        cur = self.__head
        node = Node(item)
        if self.is_empty():
            self.__head = node
        else:
            while cur.next != None:
                cur = cur.next
            cur.next = node
            node.prev = cur

    #指定位置添加元素
    def insert(self, pos, item):
        if pos <= 0:
            self.add(item)
            return
        elif pos >= self.length():
            self.append(item)
            return
        #pos 从0开始
        cur = self.__head
        node = Node(item)
        i = 0
        while i < pos:
            cur = cur.next
            i += 1
        node.next = cur
        node.prev = cur.prev
        cur.prev.next = node
        cur.prev = node




    #删除节点
    def remove(self, item):
        #通过双指针的运用，比较方便的删除节点，代码也好理解。
        cur = self.__head
        if cur == None:
            return

        while cur != None:
            if cur.elem == item:
                if cur == self.__head:
                    self.__head = cur.next
                    if cur.next:
                        cur.next.prev = None
                else:
                    cur.prev.next = cur.next
                    if cur.next:
                        cur.next.prev = cur.prev
                break
            else:
                cur = cur.next


    #查找节点是否存在
    def search(self, item):
        cur = self.__head
        count = 0
        while count < self.length():
            count += 1
            if cur.elem == item:
                return True
        return False

    # 查找节点是否存在
    def search1(self, item):
        cur = self.__head
        while cur != None:
            if cur.elem == item:
                return True
            else:
                cur = cur.next
        return False


if __name__ == "__main__":
    ll = DoubleLinkList()
    print("length:", ll.length())
    ll.append(3)
    print ("length:",ll.length())
    ll.append(2)
    ll.append(1)
    ll.travel()

    ll.add(4)
    ll.travel()

    ll.insert(-1, 6)
    ll.travel()

    ll.insert(1, 5)
    ll.travel()

    ll.insert(10, 0)
    ll.travel()

    ll.remove(6)
    ll.travel()

    ll.remove(4)
    ll.travel()

    ll.remove(0)
    ll.travel()

    ll.remove(100)
    ll.travel()

    for i  in range(0, 2000):
        ll.append(i)

    import time
    a = time.time()
    ll.search(10000)
    print("length " + str(time.time() - a))

    b = time.time()
    ll.search1(10000)
    print("no length " + str(time.time() - b))