/*** Definition for singly-linked list.* struct ListNode {*     int val;*     ListNode *next;*     ListNode(int x) : val(x), next(NULL) {}* };*/
class Solution {
public:ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {ListNode* curA = headA;ListNode* curB = headB;int sizeA=0,sizeB=0;while(curA != nullptr) {sizeA++;curA = curA->next;}while(curB != nullptr) {sizeB++;curB = curB->next;}curA = headA;curB = headB;if(sizeA > sizeB) {int temp = sizeA - sizeB;while(temp) {curA = curA->next;temp--;}}else if(sizeA < sizeB) {int temp = sizeB - sizeA;while(temp) {curB = curB->next;temp--;}}while(curA != curB) {curA = curA->next;curB = curB->next;}if(curA == NULL || curB == NULL)return NULL;else return curA;}
};

/*** 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* reverseList(ListNode* head) {ListNode* dummyHead = new ListNode(0);dummyHead->next = nullptr;ListNode* cur = head;while(cur != nullptr) {ListNode* temp = cur->next;cur->next = dummyHead->next;dummyHead->next = cur;cur = temp;}return dummyHead->next;}
};

/*** 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:bool isPalindrome(ListNode* head) {if(head==nullptr || head->next==nullptr)return true;vector<int> nums;while(head!=nullptr) {nums.push_back(head->val);head = head->next;}int size = nums.size();int i=0,j=size-1;while(i<j) {if(nums[i] == nums[j]) {i++;j--;continue;}elsereturn false;}return true;}
};

/*** Definition for singly-linked list.* struct ListNode {*     int val;*     ListNode *next;*     ListNode(int x) : val(x), next(NULL) {}* };*/
class Solution {
public:bool hasCycle(ListNode *head) {if(head==nullptr || head->next == nullptr)return false;ListNode* fast = head;ListNode* slow = head;while(fast && fast->next) {   //这里保证fast->next也不为空是因为若为空 不存在->next了fast = fast->next->next;slow = slow->next;if(slow == fast)return true;}return false;}
};

加粗样式

/*** Definition for singly-linked list.* struct ListNode {*     int val;*     ListNode *next;*     ListNode(int x) : val(x), next(NULL) {}* };*/
class Solution {
public:bool hasCycle(ListNode *head) {if(head==nullptr || head->next == nullptr)return false;ListNode* fast = head;ListNode* slow = head;while(fast && fast->next) {   //这里保证fast->next也不为空是因为若为空 不存在->next了fast = fast->next->next;slow = slow->next;if(slow == fast)return true;}return false;}
};