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代码随想录算法训练营第三天 | 203.移除链表元素、707.设

代码随想录算法训练营第三天 | 203.移除链表元素、707.设

作者: Luke_Lu | 来源:发表于2023-06-30 21:11 被阅读0次
    class Solution:
        def removeElements(self, head: Optional[ListNode], val: int) -> Optional[ListNode]:
            # 创建虚拟头部节点以简化删除过程
            dummy_head = ListNode(next = head)
            
            # 遍历列表并删除值为val的节点
            current = dummy_head
            while current.next:
                if current.next.val == val:
                    current.next = current.next.next
                else:
                    current = current.next
            
            return dummy_head.next
    
    class ListNode:
        def __init__(self, val=0, next=None):
            self.val = val
            self.next = next
            
    class MyLinkedList:
        def __init__(self):
            self.dummy_head = ListNode()
            self.size = 0
    
        def get(self, index: int) -> int:
            if index < 0 or index >= self.size:
                return -1
            
            current = self.dummy_head.next
            for i in range(index):
                current = current.next
                
            return current.val
    
        def addAtHead(self, val: int) -> None:
            self.dummy_head.next = ListNode(val, self.dummy_head.next)
            self.size += 1
    
        def addAtTail(self, val: int) -> None:
            current = self.dummy_head
            while current.next:
                current = current.next
            current.next = ListNode(val)
            self.size += 1
    
        def addAtIndex(self, index: int, val: int) -> None:
            if index < 0 or index > self.size:
                return
            
            current = self.dummy_head
            for i in range(index):
                current = current.next
            current.next = ListNode(val, current.next)
            self.size += 1
    
        def deleteAtIndex(self, index: int) -> None:
            if index < 0 or index >= self.size:
                return
            
            current = self.dummy_head
            for i in range(index):
                current = current.next
            current.next = current.next.next
            self.size -= 1
    
    class Solution:
        def reverseList(self, head: ListNode) -> ListNode:
            dummy = None
            while head is not None:
                tmp = head.next
                head.next = dummy
                dummy = head
                head = tmp
            return dummy
    

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