线性表——双向链表

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <ctime> 

using namespace std;

using ElemType = int;

// 双向链表结点 
class Node {
public:
	ElemType data;
	Node *next;
	Node *prior; 
}; 

// 初始化链表 
void initList(Node *head, int n)
{
	srand(time(NULL));
	Node *p = head, *r = head;
	while (n--) {
		Node *q = (Node*)malloc(sizeof(Node));
		q->data = rand()%100 - 1;
		p->next = q;
		q->prior = p;
		q->next = r;
		r->prior = q;
		p = q;
	}
}

// 增加某结点 
void addNode(Node *head, int i, ElemType val)
{
	int j = 0;
	Node *p = head;
	while (1) {
		if (j == i - 1) {
			Node *q = (Node*)malloc(sizeof(Node));
			q->data = val;
			q->prior = p;
			q->next = p->next;
			p->next->prior = q;
			p->next = q;
			break;
		}
		j++;			// p指向第j个结点 
		p = p->next;
	}
}

// 删除某结点 
void delNode(Node *head, int i)
{
	int j = 0;
	Node *p = head;
	while (1) {
		if (j == i) {
			p->prior->next = p->next;
			p->next->prior = p->prior;
			break;
		}
		j++;
		p = p->next;
	}
}

// 取某结点的值 
void getNode(Node *head, int i)
{
	int j = 0;
	Node *p = head;
	while (1) {
		if (j == i) {
			cout << "第" << i << "个结点的值为：" << p->data << endl;
			break;
		}
		j++;
		p = p->next;
	}	
}

// 打印双向链表 
void print(Node *head)
{
	Node *p = head;
	p = p->next;
	while (p != head) {
		cout << p->data << " ";
		p = p->next;
	}
	cout << endl;
}


int main()
{
	Node *head = (Node*)malloc(sizeof(Node));
	head->prior = head;
	head->next = head;
	initList(head, 5);
	print(head);
	addNode(head, 2, 100);
	print(head);
	delNode(head, 2);
	print(head);
	getNode(head, 2);
}