hot100链表题

### hot100 链表算法题练习 以下是与 LeetCode Hot 100 中链表相关的经典算法题目及其简要说明： #### 1. **两数相加 (Add Two Numbers)** 这道题要求实现一个函数，输入两个非空链表，表示两个非负整数。这些数字以逆序方式存储在链表中，每个节点包含一位数字。返回一个新的链表，代表这两个数之和[^1]。 ```python class ListNode: def __init__(self, val=0, next=None): self.val = val self.next = next def addTwoNumbers(l1: ListNode, l2: ListNode) -> ListNode: dummy = ListNode() current = dummy carry = 0 while l1 or l2 or carry: v1 = l1.val if l1 else 0 v2 = l2.val if l2 else 0 total = v1 + v2 + carry carry = total // 10 current.next = ListNode(total % 10) current = current.next l1 = l1.next if l1 else None l2 = l2.next if l2 else None return dummy.next ``` --- #### 2. **删除链表的倒数第 N 个结点 (Remove Nth Node From End of List)** 此题的目标是从单链表中移除倒数第 n 个节点，并返回修改后的链表头指针。 ```python def removeNthFromEnd(head: ListNode, n: int) -> ListNode: dummy = ListNode(next=head) fast = slow = dummy for _ in range(n + 1): fast = fast.next while fast: fast = fast.next slow = slow.next slow.next = slow.next.next return dummy.next ``` --- #### 3. **合并两个有序链表 (Merge Two Sorted Lists)** 将两个升序链表合并为一个新的升序链表并返回。新链表应由原链表中的节点组成[^1]。 ```python def mergeTwoLists(list1: ListNode, list2: ListNode) -> ListNode: dummy = ListNode() tail = dummy while list1 and list2: if list1.val < list2.val: tail.next = list1 list1 = list1.next else: tail.next = list2 list2 = list2.next tail = tail.next tail.next = list1 if list1 else list2 return dummy.next ``` --- #### 4. **环形链表 (Linked List Cycle)** 判断给定链表是否存在环。如果存在环，则返回 `True`；否则返回 `False`[^2]。 ```python def hasCycle(head: ListNode) -> bool: slow = head fast = head while fast and fast.next: slow = slow.next fast = fast.next.next if slow == fast: return True return False ``` --- #### 5. **反转链表 (Reverse Linked List)** 反转一个单链表并返回新的头节点。 ```python def reverseList(head: ListNode) -> ListNode: prev = None curr = head while curr: temp = curr.next curr.next = prev prev = curr curr = temp return prev ``` --- #### 6. **回文链表 (Palindrome Linked List)** 检查一个链表是否为回文结构。 ```python def isPalindrome(head: ListNode) -> bool: values = [] while head: values.append(head.val) head = head.next return values == values[::-1] ``` --- 以上是部分经典的链表算法题目，适合初学者到中级水平的开发者进行练习。每一道题都具有一定的挑战性和实际应用价值。 --- ###