做完美文本编辑器一题时出现了runtime error，这题我是用双向链表实现的，求问大神指导出错的原因，谢谢。
题目：(https://img-mid.csdnimg.cn/release/static/image/mid/ask/005183476956116.png "#left")
#include
#include
#include
using namespace std;
struct Listnode
{
char a;
Listnode* pred; Listnode* succ;
Listnode(){ }
Listnode(char alpha, Listnode* p = nullptr, Listnode* s = nullptr):
a(alpha),pred(p),succ(s){}
Listnode* insertAsPred(const char& e) {
Listnode* x = new Listnode(e, pred, this);
pred->succ = x;
pred = x;
return x;
}
Listnode* insertAsSucc(const char& e) {
Listnode* x = new Listnode(e, this, succ);
succ->pred = x;
succ = x;
return x;
}
};
class List
{
private:
int size;
//int flag;
Listnode* header;
Listnode* trailer;
public:
void init() {
header = new Listnode;
trailer = new Listnode;
header->succ = trailer; header->pred = nullptr;
trailer->pred = header; trailer->succ = nullptr;
size = 0;
trailer->a = '-';
header->a = '-';
}
List() {
init();
}
char remove(Listnode* p)
{
char e = p->a;
p->pred->succ = p->succ;
p->succ->pred = p->pred;
delete p;
size--;
return e;
}
~List() {
while (0 < size)
{
remove(header->succ);
}
delete header;
delete trailer;
}
int get_size() {
return size;
}
Listnode* insertBefore(Listnode* p, char const& e)
{
size++; return p->insertAsPred(e);
}
Listnode* insertAsLast(char const& e)
{
size++;
return trailer->insertAsPred(e);
}
Listnode* first() const
{
return header->succ;
}
Listnode* get_trailer() const
{
return trailer;
}
void push_down_left(Listnode* p)
{
if (p->pred->succ != p)
{
Listnode* pa;
Listnode* pb = p->pred;
pa = pb->pred;
pb->pred = pb->succ;
pb->succ = pa;
}
}
void push_down_right(Listnode* p)
{
if (p->succ->pred != p)
{
Listnode* pa;
Listnode* pb = p->succ;
pa = pb->pred;
pb->pred = pb->succ;
pb->succ = pa;
}
}
};
char initial_sequence[3200010];
char curser[5];
char order[5];
char content[5];
int flag = 0;
int main()
{
//freopen("input.txt", "r", stdin);
scanf("%s", initial_sequence);
int initial_txtlen = strlen(initial_sequence);
List la;
for (int i = 0; i < initial_txtlen; i++)
{
la.insertAsLast(initial_sequence[i]);
}
Listnode* p1 = la.first();
Listnode* p2 = la.get_trailer();
int N;
scanf("%d", &N);
for (int i = 0; i < N; i++)
{
scanf("%s", order);
if (order[0] == '<')
{
scanf("%s", curser);
if (curser[0] == 'L')
{
if (p1 != la.first())
{
la.push_down_left(p1);
p1 = p1->pred;
printf("T\n");
if (flag == 2)
{
if (p1 == p2)
{
flag = 1;
}
}
else if (flag == 1)
{
flag = 0;
}
}
else
{
printf("F\n");
}
}
else
{
if (p2 != la.first())
{
la.push_down_left(p2);
p2 = p2->pred;
printf("T\n");
if (flag == 0)
{
if (p1 == p2)
{
flag = 1;
}
}
else if (flag == 1)
{
flag = 2;
}
}
else
{
printf("F\n");
}
}
}
else if (order[0] == '>')
{
scanf("%s", curser);
if (curser[0] == 'L')
{
if (p1 != la.get_trailer())
{
la.push_down_right(p1);
p1 = p1->succ;
printf("T\n");
if (flag == 0)
{
if (p1 == p2)
{
flag = 1;
}
}
else if (flag == 1)
{
flag = 2;
}
}
else
{
printf("F\n");
}
}
else
{
if (p2 != la.get_trailer())
{
la.push_down_right(p2);
p2 = p2->succ;
printf("T\n");
if (flag == 2)
{
if (p1 == p2)
{
flag = 1;
}
}
else if (flag == 1)
{
flag = 0;
}
}
else
{
printf("F\n");
}
}
}
else if (order[0] == 'I')
{
scanf("%s", curser);
scanf("%s", content);
if (curser[0] == 'L')
{
la.push_down_left(p1);
la.insertBefore(p1, content[0]);
printf("T\n");
}
else
{
la.push_down_left(p2);
la.insertBefore(p2, content[0]);
printf("T\n");
}
}
else if (order[0] == 'D')
{
scanf("%s", curser);
if (curser[0] == 'L')
{
if (p1 != la.get_trailer())
{
la.push_down_right(p1);
Listnode* pa = p1;
p1 = p1->succ;
la.remove(pa);
printf("T\n");
if (flag == 0)
{
if (p1 == p2)
{
flag = 1;
}
}
else if (flag == 1)
{
p2 = p1;
}
}
else
{
printf("F\n");
}
}
else
{
if (p2 != la.get_trailer())
{
la.push_down_right(p2);
Listnode* pa = p2;
p2 = p2->succ;
la.remove(pa);
printf("T\n");
if (flag == 2)
{
if (p1 == p2)
{
flag = 1;
}
}
else if (flag == 1)
{
p1 = p2;
}
}
else
{
printf("F\n");
}
}
}
else if (order[0] == 'R')
{
if (flag == 0)
{
Listnode* pa = p2->pred;
Listnode* pb = p1->pred;
pa->succ = pa->pred;
pa->pred = pb;
pb->succ = pa;
p1->pred = p1->succ;
p1->succ = p2;
p2->pred = p1;
p1 = pa;
printf("T\n");
}
else
{
printf("F\n");
}
}
else if (order[0] == 'S')
{
Listnode* pa = la.first();
Listnode* pb = la.first();
for (int i = 0; i < la.get_size(); i++)
{
la.push_down_right(pa);
pa = pa->succ;
}
for (int i = 0; i < la.get_size(); i++)
{
printf("%c", pb->a);
pb = pb->succ;
}
printf("\n");
}
}
return 0;
}
仅供参考：
//不带表头结点的双向链表
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <time.h>
#include <locale.h>
struct NODE {
int data;
struct NODE *next;
struct NODE *prev;
} *head,*p,*q,*s,*p1,*p2,*q1,**ta;
int i,k,n,t,m,v,N=10;
int main() {
setlocale(LC_ALL,"chs");
srand(time(NULL));
head=NULL;
printf("创建%d个节点的双向链表:",N);//创建N个节点的双向链表
p=head;
for (i=0;i<N;i++) {
q=(struct NODE *)malloc(sizeof(struct NODE));
if (NULL==q) exit(1);
q->data=rand()%100;//填写0..99的随机值
q->next=NULL;
q->prev=NULL;
if (NULL==p) {
head=q;
p=head;
} else {
p->next=q;
q->prev=p;
p=q;
}
}
//输出整个双向链表
s=head;
while (1) {
if (NULL==s) {
printf("\n");
break;
}
printf("%02d<->",s->data);
if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
s=s->next;
}
k=3;
v=5;
printf("将值为%d的结点插入到双向链表的第%d个结点前:",v,k);//将值为v的结点插入到双向链表的第k个结点前
n=0;
p=head;
while (1) {
if (NULL==p) {
break;
}
n++;
if (k==1) {
q=(struct NODE *)malloc(sizeof(struct NODE));
if (NULL==q) exit(1);
q->data=v;
q->next=head;
q->prev=NULL;
head->prev=q;
head=q;
break;
} else {
if (k-1==n) {
q=(struct NODE *)malloc(sizeof(struct NODE));
if (NULL==q) exit(1);
q->data=v;
q->next=p->next;
q->prev=p;
p->next->prev=q;
p->next=q;
break;
}
}
p=p->next;
}
//输出整个双向链表
s=head;
while (1) {
if (NULL==s) {
printf("\n");
break;
}
printf("%02d<->",s->data);
if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
s=s->next;
}
k=5;
printf("删除第%d个节点:",k);//删除第k个节点
n=0;
p=head;
while (1) {
if (NULL==p) {
break;
}
n++;
if (k==1) {
q=head;
head=head->next;
head->prev=NULL;
free(q);
break;
} else {
if (k-1==n) {
q=p->next;
if (q) {
p->next=q->next;
if (q->next) q->next->prev=p;
free(q);
}
break;
}
}
p=p->next;
}
//输出整个双向链表
s=head;
while (1) {
if (NULL==s) {
printf("\n");
break;
}
printf("%02d<->",s->data);
if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
s=s->next;
}
printf("从小到大排序:");//从小到大排序
for (p=head,p1=NULL;p!=NULL;p1=p,p=p->next) {
for (q=p->next,q1=p;q!=NULL;q1=q,q=q->next) {
if (p->data > q->data) {
//交换data
// printf("swap %02d %02d\n",p->data,q->data);
// t=p->data;p->data=q->data;q->data=t;
//或者
//交换prev和next
// printf("swap %02d %02d\n",p->data,q->data);
if (p==head) {//p是头
if (p->next==q) {//pq挨着
head=q;
head->prev=NULL;
p->next=q->next;
p->prev=q;
if (q->next) q->next->prev=p;
q->next=p;
q=p;
p=head;
} else {//pq不挨着
head=q;
head->prev=NULL;
p2=p->next;
p->next=q->next;
p->prev=q->prev;
if (q->next) q->next->prev=p;
q->next=p2;
p2->prev=q;
q1->next=p;
q=p;
p=head;
}
} else {//p不是头
if (p->next==q) {//pq挨着
p1->next=q;
p->next=q->next;
p->prev=q;
if (q->next) q->next->prev=p;
q->next=p;
q->prev=p1;
q=p;
p=p1->next;
} else {//pq不挨着
p1->next=q;
p2=p->next;
p->next=q->next;
p->prev=q->prev;
if (q->next) q->next->prev=p;
q->next=p2;
p2->prev=q;
q->prev=p1;
q1->next=p;
q=p;
p=p1->next;
}
}
//输出整个双向链表
// s=head;
// while (1) {
// if (NULL==s) {
// printf("\n");
// break;
// }
// printf("%02d<->",s->data);
// if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
// s=s->next;
// }
// getchar();
}
}
}
//输出整个双向链表并计算链表长度n
n=0;
s=head;
while (1) {
if (NULL==s) {
printf("\n");
break;
}
printf("%02d<->",s->data);
if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
n++;
s=s->next;
}
printf("将整个链表逆序:");//将整个链表逆序
if (n>=2) {
p=head;
q=p->next;
p->next=NULL;
while (1) {
q1=q->next;
q->next=p;
p->prev=q;
p=q;
q=q1;
if (NULL==q) break;
}
head=p;
head->prev=NULL;
}
//输出整个双向链表
s=head;
while (1) {
if (NULL==s) {
printf("\n");
break;
}
printf("%02d<->",s->data);
if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
s=s->next;
}
m=4;
n=6;
printf("将双向链表中前%d个结点和后%d个结点进行互换:",m,n);//将双向链表中前m个结点和后n个结点进行互换,m+n为链表总长
k=0;
p=head;
while (1) {
if (NULL==p) {
break;
}
k++;
if (m==k) {
q=p;
}
s=p;
p=p->next;
}
q1=head;
head=q->next;
head->prev=NULL;
s->next=q1;
q1->prev=s;
q->next=NULL;
//输出整个双向链表
s=head;
while (1) {
if (NULL==s) {
printf("\n");
break;
}
printf("%02d<->",s->data);
if (NULL!=s->next && s->next->prev!=s) {printf(" !\n");break;}
s=s->next;
}
//释放所有节点
p=head;
while (1) {
if (NULL==p) {
break;
}
q=p->next;
free(p);
p=q;
}
return 0;
}
//创建10个节点的双向链表:93<->03<->60<->05<->57<->71<->02<->41<->26<->85<->
//将值为5的结点插入到双向链表的第3个结点前:93<->03<->05<->60<->05<->57<->71<->02<->41<->26<->85<->
//删除第5个节点:93<->03<->05<->60<->57<->71<->02<->41<->26<->85<->
//从小到大排序:02<->03<->05<->26<->41<->57<->60<->71<->85<->93<->
//将整个链表逆序:93<->85<->71<->60<->57<->41<->26<->05<->03<->02<->
//将双向链表中前4个结点和后6个结点进行互换:57<->41<->26<->05<->03<->02<->93<->85<->71<->60<->
//