c语言-链表习题

1.尾插法 Q6544

涉及：
（1）创建链表

struct stu* createList() {
    struct stu *head = NULL, *tail = NULL, *newNode;
    char choice;
    char name[20];
    float price;
    do {
        printf("请输入书名 价格：\n");
        scanf("%s %f", name, &price);
        newNode = (struct stu*)malloc(sizeof(struct stu));
        if (newNode == NULL) {
            printf("内存分配失败\n");
            return NULL;
        }
        strcpy(newNode->name, name);
        newNode->price = price;
        newNode->next = NULL;
        if (head == NULL) {
            head = newNode;
            tail = newNode;
        } else {
            tail->next = newNode;
            tail = newNode;
        }
        printf("是否继续输入,按Y键继续输入，其他键就结束.\n");
        scanf(" %c", &choice);
    } while (choice == 'Y' || choice == 'y');
    return head;
}

往链表里一个个添加节点同理，需要注意如果是在主函数中定义的LinkList，且创建链表函数不返回结点指针的话（为void），需要传头结点的地址（尽量不用，用createList返回指针是更容易实现的。），如Q6502

int main()
{
    int choice;
    struct stu *head=NULL,*tail=NULL;
    do{
        printf("1  增加数据\n");
        printf("2  退出\n");
        printf("选择：");
        scanf("%d",&choice);
        if(choice==1){
            Append(&head,&tail);
        }
    }while(choice!=2);
    DisLink(head);
    DeleteMemory(head);
    return 0;
}
void Append(struct stu **head,struct stu **tail){
    struct stu* newNode;
    newNode=(struct stu*)malloc(sizeof(struct stu));
    if(newNode==NULL){
        printf("内存分配失败\n");
        return;
    }
    printf("请输入学号：");
    scanf("%s",newNode->ID);
    printf("请输入名字：");
    scanf("%s",newNode->name);
    printf("请依次输入语文，数学，外语成绩：");
    scanf("%d %d %d",&newNode->c1,&newNode->c2,&newNode->c3);
    newNode->next=NULL;
    if((*head)==NULL){
        (*head)=newNode;
        (*tail)=newNode;
    }
    else{
        (*tail)->next=newNode;
        (*tail)=newNode;
    }
}

（2）查找最大值

void printMostExpensive(struct stu *head) {
    if (head == NULL) {
        return;
    }
    struct stu *max = head;
    struct stu *current = head->next;
    while (current!= NULL) {
        if (current->price > max->price) {
            max = current;
        }
        current = current->next;
    }
    printf("result:\n");
    printf("%s %.2f\n", max->name, max->price);
}

（3）释放内存

void freeList(struct stu *head) {
    struct stu *temp;
    while (head!= NULL) {
        temp = head;
        head = head->next;
        free(temp);
    }
}

在这里插入图片描述
全部代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// 定义结构体
struct stu {
    char name[20];
    float price;
    struct stu *next;
};

// 创建链表函数
struct stu* createList() {
    struct stu *head = NULL, *tail = NULL, *newNode;
    char choice;
    char name[20];
    float price;
    do {
        printf("请输入书名 价格：\n");
        scanf("%s %f", name, &price);
        newNode = (struct stu*)malloc(sizeof(struct stu));
        if (newNode == NULL) {
            printf("内存分配失败\n");
            return NULL;
        }
        strcpy(newNode->name, name);
        newNode->price = price;
        newNode->next = NULL;
        if (head == NULL) {
            head = newNode;
            tail = newNode;
        } else {
            tail->next = newNode;
            tail = newNode;
        }
        printf("是否继续输入,按Y键继续输入，其他键就结束.\n");
        scanf(" %c", &choice);
    } while (choice == 'Y' || choice == 'y');
    return head;
}

// 输出最贵书籍信息函数
void printMostExpensive(struct stu *head) {
    if (head == NULL) {
        return;
    }
    struct stu *max = head;
    struct stu *current = head->next;
    while (current!= NULL) {
        if (current->price > max->price) {
            max = current;
        }
        current = current->next;
    }
    printf("result:\n");
    printf("%s %.2f\n", max->name, max->price);
}

// 释放链表内存函数
void freeList(struct stu *head) {
    struct stu *temp;
    while (head!= NULL) {
        temp = head;
        head = head->next;
        free(temp);
    }
}

int main() {
    struct stu *head = createList();
    printMostExpensive(head);
    freeList(head);
    return 0;
}
/*
Algorithms 105
Y
高等数学 31.5
Y
C语言 35
J

*/

2.排序 test3

在这里插入图片描述

（1）利用选择排序的方法，降序排序

void descLinkList(Student* head){
    Student *i,*j;
    int tempID;
    char tempName[10];
    float tempScore;
    for(i=head;i!=NULL;i=i->pNextNode){
        for(j=i->pNextNode;j!=NULL;j=j->pNextNode){
            if(i->score<j->score){
                tempID=i->ID;
                i->ID=j->ID;
                j->ID=tempID;
                strcpy(tempName,i->name);
                strcpy(i->name,j->name);
                strcpy(j->name,tempName);
                tempScore=i->score;
                i->score=j->score;
                j->score=tempScore;
            }
        }
    }
}

3.头插法 Q6815

建立带头结点的两个链表哦

void reverse_print(struct ListNode *head){
    struct ListNode *head2=(struct ListNode *)malloc(sizeof(struct ListNode));//链表2的头结点
    head2->next=NULL;
    struct ListNode *p;
    while(head->next!=NULL){
        p=head->next;
        head->next=head->next->next;
        p->next=head2->next;
        head2->next=p;
    }
    head->next=head2->next;
    free(head2);
    
    while(head->next!=NULL){//print
        printf("%d\n",head->next->val);
        head->next=head->next->next;
    }
}

4.遍历链表不许破坏链表结构

错误代码：head->next=head->next->next;破坏了链表结构，导致后续无法再使用该链表。

void show(struct goods *head){
    printf("head2 address is %p\n",head);
    printf("输出所有商品信息为：编号 类型 名称 数量:\n");
    while(head->next!=NULL){
        printf("%d %s %s %d\n",head->next->num,head->next->type,head->next->name,head->next->counts);
        head->next=head->next->next;
    }
}

正确代码：

void show(struct goods *head){
    printf("输出所有商品信息为：编号 类型 名称 数量:\n");
    struct goods *p=head->next;
    while(p!=NULL){
        printf("%d %s %s %d\n",p->num,p->type,p->name,p->counts);
        p=p->next;
    }
}