#include <iostream>
using namespace std;
typedef int ElemType;
// 3. 双链表
typedef struct DNode
{ElemType data;struct DNode *prior, *next;
} DNode, *DLinkList;
// 初始化带头结点
bool InitDNodeList(DLinkList &L)
{L = (DNode *)malloc(sizeof(DNode));if (L == NULL){return false;}L->prior = NULL;L->next = NULL;return true;
}
// 在第 i 个位置插入元素 e
bool InsertDNodeList(DLinkList &L, int i, ElemType e)
{DNode *p = L, *s;int j = 0;while (p != NULL && j < i - 1){p = p->next;j++;}if (p == NULL){cout << "插入位置不合法" << endl;return false;}s = (DNode *)malloc(sizeof(DNode));s->data = e;// 判断是否在空表中插入if (p->next == NULL){s->next = NULL;s->prior = p;p->next = s;return true;}else{s->next = p->next;s->prior = p;p->next->prior = s;p->next = s;return true;}
}
// 删除第 i 个元素，并返回元素 e
bool DeleteDNodeList(DLinkList &L, int i, ElemType &e)
{DNode *p = L, *q;int j = 0;while (p != NULL && j < i - 1){p = p->next;j++;}if (p == NULL){cout << "删除位置不合法" << endl;return false;}q = p->next;e = q->data;p->next = q->next;q->next->prior = p;free(q);return true;
}
// 遍历双链表
void TraverseDNodeList(DLinkList L)
{DNode *p = L->next;while (p != NULL){cout << p->data << " ";p = p->next;}cout << endl;
}
int main()
{DLinkList L;ElemType e;InitDNodeList(L);InsertDNodeList(L, 1, 1);InsertDNodeList(L, 2, 2);InsertDNodeList(L, 3, 3);TraverseDNodeList(L);DeleteDNodeList(L, 2, e);cout << "删除元素为：" << e << endl;TraverseDNodeList(L);return 0;
}