数据结构学习

链表

单链表

__author__ = "Hao Rui Chun"


class Node():
    def __init__(self, item):
        self.item = item
        self.next = None


class SingleLink():
    def __init__(self):
        # 构造一个空列表，这个头指针只能为空或者指定第一个节点的地址
        self._head = None

    def add(self, item):
        node = Node(item)
        # 单链表的最后一个结点指向的是 NULL,所以需要将头节点的next赋值给新节点的next
        node.next = self._head
        # 接着，我们将数据域，也就是 node 的地址赋给 head->next， 这时 head->next 指向的就是新创建的 node的地址。而 node 指向的就是 NULL
        self._head = node

    def travel(self):
        cur = self._head
        while cur:
            print(cur.item)
            cur = cur.next

    def len(self):
        cur = self._head
        i = 0
        while cur:
            i += 1
            cur = cur.next
        return i

    def isEmpty(self):
        return self._head == None

    def append(self, item):
        node = Node(item)
        if self.isEmpty():
            self._head = node
            return
        else:
            cur = self._head
            while cur.next:
                cur = cur.next
            cur.next = node

    def insert(self,index,item):
        node = Node(item)
        cur = self._head
        count = 0
        if self.isEmpty():
            self.add(item)
        elif index > self.len()-1:
            self.append(item)
        else:
            while count < index-1:
                cur = cur.next
                count += 1
            node.next = cur.next
            cur.next = node

    def remove(self,item):
        if self.isEmpty():
            return False
        else:
            cur = self._head
            pre =None
            while cur.next:
                if cur.item == item:
                    if cur == self._head:
                        #正好是头节点
                        self._head = cur.next
                    else:
                        #中间节点
                        pre.next =cur.next
                    return
                else:
                    pre =cur
                    cur =cur.next
            else:
                #尾节点
                if cur.item == item:
                    if cur == self._head:
                        self._head = None
                    else:
                        pre.next = cur.item



    def search(self,item):
        cur =self._head
        while cur.next:
            if cur.item == item:
                return True
            else:
                cur =cur.next
        if cur.item == item:
            return True
        else:
            return False


if __name__ == '__main__':
    link = SingleLink()
    link.add(3)
    link.add(4)
    link.add(5)
    link.append(100)
    link.insert(1,200)
    link.travel()
    print(link.search(100))
    link.remove(3)
    link.travel()

单向循环链表

__author__ = "Hao Rui Chun"


class Node():
    def __init__(self, item):
        self.item = item
        self.next = None


class WhileLink(object):
    def __init__(self,node=None):
        if node:
            node.next = node
        self._head = node

    def isEmpty(self):
        return self._head == None

    def len(self):
        if self.isEmpty():
            return 0
        cur = self._head
        count = 1
        while cur.next != self._head:
            count += 1
            cur = cur.next
        return count

    def travel(self):
        if self.isEmpty():
            return None
        cur = self._head
        while cur.next != self._head:
            print(cur.item,end=' ')
            cur = cur.next
        # 循环结束，cur指向尾节点
        print(cur.item)

    def add(self,item):
        node = Node(item)
        cur = self._head
        if self.isEmpty():
            node.next = self._head
            self._head = node
            return
        while cur.next != self._head:
            cur = cur.next
        #循环结束，cur指向尾节点

        node.next = self._head
        self._head = node
        #cur.next = node
        cur.next = self._head

    def append(self,item):
        node = Node(item)
        cur = self._head
        if self.isEmpty():
            self._head = node
            node.next = self._head
            return

        while cur.next != self._head:
            cur = cur.next
        node.next = cur.next
        cur.next = node
        # cur.next = node
        # node.next = self._head

    def insert(self,index,item):
        if self.isEmpty():
            self.add(item)
        elif index > self.len()-1:
            self.append(item)
        else:
            node = Node(item)
            cur = self._head
            count = 0
            while count < index-1:
                cur = cur.next
                count +=1
            node.next = cur.next
            cur.next = node

    def remove(self,item):
        cur = self._head
        pre =None
        while cur.next != self._head:
            if cur.item == item:
                if cur == self._head:
                    #正好是头节点,1.将头节点指向这个节点的next节点 2.将为节点指向这个节点的next节点
                    #先找到尾节点
                    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
        # 循环结束，cur指向尾节点
        if cur.item == item:
            if cur == self._head:
                #恰好只有一个节点
                self._head = None
            else:
                pre.next = cur.next

    def search(self,item):
        if self.isEmpty():
            return False
        cur = self._head
        while cur.next != self._head:
            if cur.item == item:
                return True
            else:
                cur =cur.next
        if cur.item == item:
            return True
        else:
            return False

if __name__ == '__main__':
    lis = WhileLink()
    lis.append(3)
    lis.append(4)
    lis.append(5)
    lis.add(7)
    lis.add(8)
    lis.add(9)
    lis.insert(2,100)
    lis.travel()
    print(lis.search(100))
    print(lis.len())
    lis.remove(5)
    lis.travel()