LeetCode 2. add two numbers && 单链表

add two numbers

看题一脸懵逼，看中文都很懵逼，链表怎么实现的，点了debug才看到一些代码

改一下，使本地可以跑起来

# Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution:
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        print(listNodeToString(l1))
        print(l1.val)
        print(l1.next.val)

def stringToListNode(input):
    numbers=input
    # Now convert that list into linked list
    dummyRoot = ListNode(0)
    ptr = dummyRoot
    for number in numbers:
        ptr.next = ListNode(number)
        ptr = ptr.next

    ptr = dummyRoot.next
    return ptr

def listNodeToString(node):
    if not node:
        return "[]"

    result = ""
    while node:
        result += str(node.val) + ", "
        node = node.next
    return "[" + result[:-2] + "]"

def main():

    while True:
        try:

            line = [2,4,3]
            l1 = stringToListNode(line);
            line = [5,6,4]
            l2 = stringToListNode(line);

            ret = Solution().addTwoNumbers(l1, l2)

            out = listNodeToString(ret);
            print(out)

            #throw
            raise StopIteration
        except StopIteration:
            break

if __name__ == '__main__':
    main()

第1次提交

# Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None

############## start ##############

def listNodeToInt(listN):
    '''链表转整数'''
    result=0
    i=0
    node=listN
    while True:

        if not isinstance(node,ListNode):
            break
        result += node.val*10**i
        node=node.next
        i+=1

    return result

def intToListNode(num):
    '''整数转链表，抄袭stringToListNode '''
    dummyRoot = ListNode(0)
    ptr = dummyRoot
    while True:
        if num == 0:
            break
        number=num%10
        num=num//10

        ptr.next = ListNode(number)
        ptr = ptr.next

    ptr = dummyRoot.next
    return ptr

class Solution:
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        #list1=listNodeToString(l1)
        #print(list1)

        i1=listNodeToInt(l1)
        i2=listNodeToInt(l2)
        i3=i1+i2
        #print(i1,i2)
        #print(i3)
        l3=intToListNode(i3)
        #print(listNodeToString(l3))

        return l3

##############  end  ##############   

def stringToListNode(input):
    numbers=input
    # Now convert that list into linked list
    dummyRoot = ListNode(0)
    ptr = dummyRoot
    for number in numbers:
        ptr.next = ListNode(number)
        ptr = ptr.next

    ptr = dummyRoot.next
    return ptr

def listNodeToString(node):
    if not node:
        return "[]"

    result = ""
    while node:
        result += str(node.val) + ", "
        node = node.next
    return "[" + result[:-2] + "]"

def main():

    while True:
        try:

            line = [2,4,3]
            l1 = stringToListNode(line);
            line = [5,6,4]
            l2 = stringToListNode(line);

            ret = Solution().addTwoNumbers(l1, l2)

            out = listNodeToString(ret);
            print(out)

            #throw
            raise StopIteration
        except StopIteration:
            break

if __name__ == '__main__':
    main()

加了两个函数整数转链表和链表转整数

Wrong Answer:

Input:
[0]
[0]
Output:
[]
Expected:
[0]

应该是整数转链表时num==0直接跳过了，在前面用number当个标志位就好了

def intToListNode(num):
    '''整数转链表，抄袭stringToListNode '''
    dummyRoot = ListNode(0)
    ptr = dummyRoot
    number=-1
    while True:
        if num == 0:
            if number==-1:
                ptr.next=ListNode(0)
            break
        number=num%10
        num=num//10

        ptr.next = ListNode(number)
        ptr = ptr.next

    ptr = dummyRoot.next
    return ptr

提交AC。

总结：学到了链表？？既然没学懂，就去弄个链表。

#

class Node(object):
    '''节点类'''

    def __init__(self,data, pnext=None):
        '''
        	data: 节点保存的数据
        	_next: 保存下一个节点对象
        '''
        self.data = data
        self._next = pnext

    def __repr__(self):
        return str(self.data)

class ListNode(object):
    '''链表类'''
    def __init__(self):
    	self.head=None
    	self.lenght=0

    def isEmpty(self):
    	'''判断是否为空'''
    	return (self.length==0)

    def append(self,data):
        '''增加一个节点'''
        item=None
        if isinstance(data,Node):
            item = data
        else:
            item = Node(data)

        #如果头不存在
        if not self.head:
            self.head = item
            self.length = 1
        else:
            # 如果存在找到末尾然后添加节点
            node = self.head
            while node._next:
                node = node._next
            node._next=item
            self.length+=1

    def delete(self,index):
        '''删除一个节点'''
        if self.isEmpty():
            print("listNode is empty")
            return False

        # 删除头节点
        if index == 0:
            self.head=self.head._next
            self.length-=1
            return True

        j=0
        node = self.head
        prev = self.head
        while node._next and j<index:
            prev=node
            node=node._next
            j+=1

        if j==index:
            prev._next = node._next
            self.length-=1

    def getNode(self,index,data=None,update=False):
        '''查找节点'''
        if self.isEmpty():
            print("listNode is empty")
            return False
        j=0
        node=self.head
        while node._next and j<index:
            node = node._next
            j+=1

        # 更新
        if update:
            if j==index:
                node.data=data
            return   

        return node.data

    def update(self,index,data):
        '''更新节点'''
        self.getNode(index,data,True)

    def getIndex(self,data):
        '''查找索引'''
        if self.isEmpty():
            print("listNode is empty")
            return False

        # 索引列表
        index=[]

        j=0
        node=self.head
        while node:
            if node.data == data:
                index.append(j)
            node=node._next
            j+=1

        indexLen=len(index)
        if indexLen==0:
            return False
        elif indexLen==1:
            return index[0]
        else:
            print(" index not only , is list. ")
            return index

    def insert(self,index,data):
        '''插入节点'''
        if self.isEmpty():
            print("listNode is empty, so append data")
            index=0
            self.head=None
            self.append(data)
            return True

        item = None
        if isinstance(data,Node):
            item = data
        else:
            item = Node(data)

        if index==0:
            item._next = self.head
            self.head = item
            self.length += 1

        j = 0
        node = self.head
        prev = self.head
        while node._next and j<index:
            prev=node
            node=node._next
            j+=1

        if j == index :
            item._next = node
            prev._next = item
            return True 

    def clear(self):
        self.head = None
        self.length = 0

    def __repr__(self):
        '''字符串'''
        if not self.head:
            return ' empty listNode '

        s=[]
        node = self.head
        while node:
            s.append(str(node.data))
            node = node._next

        return " -> ".join(s)

    def __getitem__(self,index):
        '''索引取值'''
        return self.getNode(index)

    def __setitem__(self,index,value):
        '''设置值'''
        print(index)
        self.update(index,value)

if __name__ == '__main__':

    # 创建链表
    chain=ListNode()

    # 添加数据
    print("add 10 numbers")
    for i in range(10,20):
        chain.append(i)

    print(chain)    

    # 查找索引
    print("value eq 12 is index = ",end=" ")
    print(chain.getIndex(12))

    # 更新上面查找的索引
    print("update  ")
    index=chain.getIndex(12)
    if isinstance(index,int):
        chain.update(index,99)

    # 再次查找索引
    print("again, value eq 12 is index = ",end=" ")
    print(chain.getIndex(12))

    print(" because listNode is : ")
    print(chain)

    # 删除一个索引
    print("delete index 0")
    chain.delete(0)
    print(chain)

    # insert
    print("insert data")
    chain.insert(1,9)
    print(chain)

    # 直接索引获取值
    print("use [] get data")
    print(chain[3])

    # 直接设置值
    print("append same value")
    chain.append(90)
    chain.append(90)
    print(chain)

    # 查找相同值索引
    print("search 90 index")
    print(chain.getIndex(90))

参考python数据结构之链表（一）