题解 | 牛牛的链表交换

#include <stdio.h>
#include <stdlib.h>
// write your code here......
struct node 
{
    int data;
    struct node* Next;
};

struct node* list_create(int arr[],int n){
    struct node* list=(struct node*)malloc(sizeof(struct node));
    struct node* p=list;
    for(int i=0; i<n; i++){
        struct node* newnode = (struct node*)malloc(sizeof(struct node));
        newnode->data=arr[i];
        p->Next=newnode;
        p=p->Next;
    }
    p->Next=NULL;
    return list;
}

void list_out(struct node* list)
{
    if(list==NULL){
        return ;
    }
    for(struct node* p=list->Next;p;p=p->Next){
        printf("%d ",p->data);
    }

}

void qianhuan(struct node* list)
{
    if(list==NULL || list->Next==NULL || list->Next->Next==NULL)
    {
        return;
    }

    struct node* first=list->Next;
    struct node* second=first->Next;

    first->Next=second->Next;
    second->Next=first;
    list->Next=second;
}

void houhuan(struct node* list)
{
    if(list==NULL || list->Next==NULL || list->Next->Next==NULL)
    {
        return;
    }
    struct node* prev= list;
    struct node* current= list->Next;
    while(current->Next->Next!=NULL)
    {
        prev=current;
        current=current->Next;
    }

    struct node* last=current->Next;
    current->Next=NULL;
    last->Next=current;
    prev->Next=last;
}

int main() {

    int n;
    scanf("%d",&n);

    int* arr=(int*)malloc(n*sizeof(int));

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

    // write your code here......
    struct node* list=list_create(arr,n);
    qianhuan(list);
    houhuan(list);
    list_out(list);

    free(arr);
    return 0;
}