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发表于 2023-6-29 14:44:22
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本帖最后由 歌者文明清理员 于 2023-6-29 14:48 编辑
这段代码在执行反转函数后打印出来是NULL的原因是反转函数fz中缺少了一个判断条件。具体来说，在while(head->next)循环体内部，对于每一段长度为K的子链表，没有判断该子链表是否有K个元素，即链表长度不足K时，跳过该子链表的反转操作。
为了修复该问题，你可以在dg函数中添加一个判断条件，当遍历到链表结尾或者已经反转了K个元素时，返回当前子链表的最后一个节点指针temp。然后在fz函数中，根据返回的最后一个节点指针temp判断当前子链表是否有K个元素，如果有则进行反转操作，否则直接结束循环。
下面是修复后的代码：
void fz(list head,int k) {
while(head->next) {
int i = 1;
list temp = head->next;
while (temp && i < k) {
temp = temp->next;
i++;
}
if (!temp) {
break; // 子链表长度不足K时结束循环
}
head->next = dg(head, head->next, 1, k);
}
}
list dg(list p,list head,int i,int k) {
list temp = NULL;
list perv = NULL;
if(i != k) {
perv = p;
p = p->next;
i++;
temp = dg(p,head,i,k);
}
else {
head->next = p->next;
temp = p->next->next;
p->next->next = p;
return temp;
}
if(i == 2) {
p->next = temp;
}
else {
perv->next->next = perv;
}
return temp;
}
完整修复后的代码如下：
#include<stdio.h>
#include<stdlib.h>
typedef struct List *list;
struct List {
int address;
int data;
int last;
list next;
};
list read(int n);
void print(list head);
void px(list head,int first);
list dg(list p,list head,int i,int k);
void fz(list head,int k);
void cleanup(list head);
void print(list head) {
if (!(head->next)) {
printf("NULL\n");
return;
}
head = head->next;
while(head) {
printf("%05d %d %05d\n",head->address,head->data,head->last);
head = head->next;
}
}
list read(int n) {
list head,p,temp;
head = p = (list)malloc(sizeof(struct List));
head->next = NULL;
while (n--) {
temp = (list)malloc(sizeof(struct List));
scanf("%d %d %d",&temp->address,&temp->data,&temp->last);
p->next = temp;
p = p->next;
p->next = NULL;
}
return head;
}
void px(list head,int first) {
list p = head;
list temp,temp2;
int t = first;
while (head->next) {
if (head->next->address == t) {
head = head->next;
t = head->last;
}
else {
p = head;
while (p->next->address != t) {
p = p->next;
}
list s;
s = p->next;
temp = s->next;
s->next = head->next;
head->next = s;
p->next = temp;
head = head->next;
t = head->last;
}
}
}
void fz(list head,int k) {
while (head->next) {
int i = 1;
list temp = head->next;
while (temp && i < k) {
temp = temp->next;
i++;
}
if (!temp) {
break; // 子链表长度不足K时结束循环
}
head->next = dg(head, head->next, 1, k);
}
}
list dg(list p,list head,int i,int k) {
list temp = NULL;
list perv = NULL;
if(i != k) {
perv = p;
p = p->next;
i++;
temp = dg(p,head,i,k);
}
else {
head->next = p->next;
temp = p->next->next;
p->next->next = p;
return temp;
}
if(i == 2) {
p->next = temp;
}
else {
perv->next->next = perv;
}
return temp;
}
void cleanup(list head) {
list temp;
while (head) {
temp = head;
head = head->next;
free(temp);
}
}
int main(void) {
list head,pxhead;
int first,n,k;
scanf("%d %d %d",&first,&n,&k);
head = read(n);
px(head,first);
fz(head,k);
print(head);
cleanup(head);
return 0;
}
希望对你有帮助！如果还有其他问题，请随时提问。
带注释版本：
以下是带有注释的修复后代码：
#include<stdio.h>
#include<stdlib.h>
typedef struct List *list;
struct List {
int address;
int data;
int last;
list next;
};
// 读取链表数据
list read(int n);
// 打印链表
void print(list head);
// 根据首地址进行链表排序
void px(list head, int first);
// 递归反转子链表
list dg(list p, list head, int i, int k);
// 反转链表中的每个子链表
void fz(list head, int k);
// 释放链表动态内存
void cleanup(list head);
// 打印链表
void print(list head) {
if (!(head->next)) {
printf("NULL\n");
return;
}
head = head->next;
while (head) {
printf("%05d %d %05d\n", head->address, head->data, head->last);
head = head->next;
}
}
// 读取链表数据
list read(int n) {
list head, p, temp;
head = p = (list)malloc(sizeof(struct List));
head->next = NULL;
while (n--) {
temp = (list)malloc(sizeof(struct List));
scanf("%d %d %d", &temp->address, &temp->data, &temp->last);
p->next = temp;
p = p->next;
p->next = NULL;
}
return head;
}
// 根据首地址进行链表排序
void px(list head, int first) {
list p = head;
list temp, temp2;
int t = first;
while (head->next) {
if (head->next->address == t) {
head = head->next;
t = head->last;
} else {
p = head;
while (p->next->address != t) {
p = p->next;
}
list s;
s = p->next;
temp = s->next;
s->next = head->next;
head->next = s;
p->next = temp;
head = head->next;
t = head->last;
}
}
}
// 反转链表中的每个子链表
void fz(list head, int k) {
while (head->next) {
int i = 1;
list temp = head->next;
while (temp && i < k) {
temp = temp->next;
i++;
}
if (!temp) {
break; // 子链表长度不足K时结束循环
}
head->next = dg(head, head->next, 1, k);
}
}
// 递归反转子链表
list dg(list p, list head,int i,int k) {
list temp = NULL;
list perv = NULL;
if(i != k) {
perv = p;
p = p->next;
i++;
temp = dg(p, head, i, k);
} else {
head->next = p->next;
temp = p->next->next;
p->next->next = p;
return temp;
}
if (i == 2) {
p->next = temp;
} else {
perv->next->next = perv;
}
return temp;
}
// 释放链表动态内存
void cleanup(list head) {
list temp;
while (head) {
temp = head;
head = head->next;
free(temp);
}
}
int main(void) {
list head, pxhead;
int first, n, k;
scanf("%d %d %d", &first, &n, &k);
head = read(n);
px(head, first);
fz(head, k);
print(head);
cleanup(head);
return 0;
}
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