VS 上手撕反转链表题（注意链表结构体的定义及链表的初始化）

#include 

using namespace std;

struct ListNode {
	int val;
	ListNode* next;
	ListNode():val(0),next(nullptr){}
	ListNode(int _val):val(_val),next(nullptr){}
	ListNode(int _val,ListNode* _next):val(_val),next(_next){}
};

ListNode* init() {
	ListNode* head = new ListNode(1);
	ListNode* node1 = new ListNode(2);
	ListNode* node2 = new ListNode(3);
	ListNode* node3 = new ListNode(4);
	ListNode* node4 = new ListNode(5);

	head->next = node1;
	node1->next = node2;
	node2->next = node3;
	node3->next = node4;
	node4->next = nullptr;
	return head;
}

ListNode* reverse(ListNode* head) {
	ListNode* pre = nullptr;
	ListNode* cur = head;
	
	
	while (cur != nullptr) {
		ListNode* nt = cur->next;
		cur->next = pre;
		pre = cur;
		cur = nt;
	}
	return pre;
}

int main() {
	auto head = init();
	head = reverse(head);
	while (head != nullptr) {
		cout << head->val << " ";
		head = head->next;
	}
	return 0;
}