Reverse a linked list【1月17日学习笔记·】

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//Reversse a linked list
#include<iostream>
using namespace std;
struct node {
	int data;
	node* next;
};
node* A;

void reverse() {
	node* next;//用于保存下一个节点地址以便索引
	node* current = A;//当前索引
	node* prev = NULL;//保存上一个节点地址

	while (current != NULL) {
		next = current->next;//指向下一节点
		current->next = prev;//当前节点尾巴指向上一节点
		prev = current;//更新，指向当前节点
		current = next;//索引指向下一节点
	}
	A = prev;//头指针指向末节点
}//头指针为空或只有一个节点时仍适用

void insert(int x) {
	node* temp = new node;
	temp->data = x;
	temp->next = NULL;

	if (A == NULL) {
		A = temp;
	}//头指针为空时要建立globle区与heap区的link才能通过头指针索引
	else {
		node* run = A;
		while (run->next != NULL) {
			run = run->next;
		}
		run->next = temp;
	}//头指针不为空时用遍历指针索引
}

void print() {
	node* run = A;
	while (run != NULL) {
		cout << run->data << " ";
		run = run->next;
	}
	cout << endl;
}

int main() {
	A = NULL;
	insert(2);
	insert(4);
	insert(6);
	insert(8);
	print();
	reverse();
	print();
}