2024.5.11-2024.5.15
移除链表元素
python
#判断头节点是否空，
#并且头节点为要删除的值，头节点向后移
while head and head.val==val:
head=head.next
if not head: return
cur=head
#当前指针指向的下一个元素为val,当前指针指向下一个的下一个
#否则，当前指针向后移动一位
while cur.next:
if cur.next.val==val:
cur.next=cur.next.next
else:
cur=cur.next
return head设计链表
css
class ListNode:
def __init__(self,val):
self.val=val
self.next=None
class MyLinkedList(object):
def __init__(self):
self.size=0
self.head=ListNode(0)
def get(self, index):
"""
:type index: int
:rtype: int
"""
if index<0 or index>=self.size:
return -1
cur=self.head
for i in range(index+1):
cur=cur.next
return cur.val
def addAtHead(self, val):
"""
:type val: int
:rtype: None
"""
#这个是实现从头部节点加入数据的代码部分
# p=ListNode(val)
# p.next=self.head.next
# self.head.next=p
# self.size+=1
#这个是调用类内已经写好的addAtIndex函数
self.addAtIndex(0,val)
def addAtTail(self, val):
"""
:type val: int
:rtype: None
"""
#这个是实现从尾部节点加入数据的代码部分
# cur=self.head
# p=ListNode(val)
# p.next=None
# for i in range(self.size):
# cur=cur.next
# cur.next=p
# self.size+=1
#这个是调用类内已经写好的addAtIndex函数
self.addAtIndex(self.size,val)
def addAtIndex(self, index, val):
"""
:type index: int
:type val: int
:rtype: None
"""
if index<0 or index>self.size:
return -1
cur=self.head
for i in range(index):
cur=cur.next
p=ListNode(val)
p.next=cur.next
cur.next=p
self.size+=1
def deleteAtIndex(self, index):
"""
:type index: int
:rtype: None
"""
if index<0 or index>=self.size:
return -1
cur=self.head
for i in range(index):
cur=cur.next
cur.next=cur.next.next
self.size-=1反转链表
自己实现的
python
pre=None
cur=head
if cur==None: return head
tmp=cur.next
while tmp:
cur.next=pre
pre=cur
cur=tmp
tmp=tmp.next
cur.next=pre
return cur参照代码随想录更改的
python
pre=None
cur=head
while cur:
tmp=cur.next
cur.next=pre
pre=cur
cur=tmp
return pre两两交换链表中的节点
我的垃圾代码，拼拼凑凑
python
dummy_head = ListNode(next = head)
pre=dummy_head
if dummy_head.next==None: return head
cur=pre.next
beh=cur.next
while beh:
tmp=beh.next
pre.next=beh
beh.next=cur
cur.next=tmp
pre=cur
cur=tmp
if tmp!=None:
beh=tmp.next
else:
beh=None
return dummy_head.next删除链表中的倒数第N个节点
python
dummy=ListNode(next=head)
slow=dummy
fast=dummy
for i in range(n):
fast=fast.next
while fast.next:
fast=fast.next
slow=slow.next
slow.next=slow.next.next
return dummy.next 链表相交
python
p1,p2=headA,headB
Asize,Bsize=0,0
while p1:
p1=p1.next
Asize+=1
while p2:
p2=p2.next
Bsize+=1
if Asize-Bsize>=0:
p1,p2=headB,headA
Asize,Bsize=Bsize,Asize
else:
p1,p2=headA,headB
for _ in range(Bsize-Asize):
p2=p2.next
while p1:
if p1==p2:
return p1
p1=p1.next
p2=p2.next
return None环形链表II
python
fast,slow=head,head
while fast and fast.next:
fast=fast.next.next
slow=slow.next
if slow==fast:
x1=head
x2=slow
while x1!=x2:
x1=x1.next
x2=x2.next
return x1