题解 | #牛牛的链表交换#

#include <stdio.h>
#include<malloc.h>

struct Node {
    int val;
    struct Node* next;

};

//创建
struct Node* createNode(int val) {
    struct Node* p = NULL;
    p = (struct Node*)malloc(sizeof(struct Node));
    if (p == NULL) {
        printf("创建失败！\n");
        return NULL;
    }
    p->val = val; //f赋值
    p->next = NULL;
    return p;
}

//插入
void insertNode(struct Node* q, int val) {
    struct Node* p;
    p = (struct Node*)malloc(sizeof(struct Node));
    if (p == NULL) {
        printf("创建失败！\n");
        return ;
    }
    p->val = val;
    p->next = q->next;
    q->next = p;
}

void changeNode(struct Node* head,int n)
{
      struct Node *l = head;
    for(int i = 1;i<n;i++)
    {
        if(i == 1||i == n-1)
        {
            int temp = head->val;
            head->val = head->next->val;
            head->next->val = temp;
        }
        head=head->next;
    }
    head = l;
}




//打印
void printfNode(struct Node* p)
{
     struct Node* head =p;
     while(head->next!=NULL)
     {
         printf("%d ",head->val);
         head=head->next;
     }
}

int main() {
    int n, i;
    scanf("%d", &n);
    int* arr = (int*)malloc(sizeof(int) * n);
    struct Node* head = createNode(0); //创建链表
    struct Node* p = head;

    for (i = 0; i < n; i++)
        scanf("%d", &arr[i]);

    head->val = arr[0];
    for (i = 1; i <= n; i++) {
        insertNode(p, arr[i]);
        p = p->next;
    }
    changeNode(head,n);
    printfNode(head);
   
    free(p);
    return 0;
}

写的眼睛都花了