文章目录 【LC刷题】DAY02：24 19 142 24. 两两交换链表中的节点 [link](https://leetcode.cn/problems/swap-nodes-in-pairs/description/) 19.删除链表的倒数第N个节点 [link](https://leetcode.cn/problems/remove-nth-node-from-end-of-list/submissions/538154299/) 面试题 02.07. 链表相交 [link](https://leetcode.cn/problems/intersection-of-two-linked-lists-lcci/description/) 142.环形链表II
24. 两两交换链表中的节点 link
/*** Definition for singly-linked list.* struct ListNode {* int val;* ListNode *next;* ListNode() : val(0), next(nullptr) {}* ListNode(int x) : val(x), next(nullptr) {}* ListNode(int x, ListNode *next) : val(x), next(next) {}* };*/
class Solution {
public:ListNode* swapPairs(ListNode* head) {ListNode* dummyHead = new ListNode(0);dummyHead->next = head;ListNode* temp = dummyHead;while(temp->next!=nullptr && temp->next->next != nullptr){ListNode *node1 = temp->next;ListNode *node2 = node1->next;temp->next = node2;node1->next = node2->next;node2 -> next = node1;temp = node1;}return dummyHead->next;}
};
19.删除链表的倒数第N个节点 link
class Solution {
public:int getLength(ListNode* head) {int length = 0;while (head) {++length;head = head->next;}return length;}ListNode* removeNthFromEnd(ListNode* head, int n) {ListNode* dummy = new ListNode(0, head);int length = getLength(head);ListNode* cur = dummy;for (int i = 1; i < length - n + 1; ++i) {cur = cur->next;}cur->next = cur->next->next;ListNode* ans = dummy->next;delete dummy;return ans;}
};面试题 02.07. 链表相交 link
class Solution {
public:ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {unordered_set<ListNode *> visited;ListNode *temp = headA;while (temp != nullptr) {visited.insert(temp);temp = temp->next;}temp = headB;while (temp != nullptr) {if (visited.count(temp)) {return temp;}temp = temp->next;}return nullptr;}
};/*** Definition for singly-linked list.* struct ListNode {* int val;* ListNode *next;* ListNode(int x) : val(x), next(NULL) {}* };*/
class Solution {
public:ListNode *detectCycle(ListNode *head) {if (head == NULL)return NULL;ListNode *fast, *slow;fast = head;slow = head->next;if(fast == slow){return head;}while(fast->next!=NULL){fast=fast->next;slow = head;while(slow != fast || slow == fast->next ){if(fast->next == slow){return slow;}slow=slow->next;}}return NULL;}
};
)
