链表逆置C语言完整代码

链表逆置C语言完整代码

#include<stdio.h>

typedef struct node {
    int num;
    struct node *next;
}Lnode;



Lnode *createlink(int n)
{
    int num;
    Lnode *head = NULL;
    Lnode *pend = head;
    
    while (n > 0)
    {
        scanf("%d", &num);
        Lnode *pnew = (struct node*)malloc(sizeof(struct node));
        pnew->num = num;
        pnew->next = NULL; //新创建的指针的下一个位置还没有定
        if (head == NULL)
        {
            head = pnew;
            pend = pnew;
        }
        else
        {
            pend->next = pnew;
            pend = pnew;
        }
        n--;
    }
    
    return head;
}


int isPalindrome(Lnode* head) {//O(n)、O(1)
    Lnode* slow = head, *fast = head, *prev = NULL;
    while (fast) {//find mid node
        slow = slow->next;
        fast = fast->next ? fast->next->next : fast->next;
    }
    while (slow) {//reverse
        Lnode* ovn = slow->next;
        slow->next = prev;
        prev = slow;
        slow = ovn;
    }
    while (head && prev) {//check
        if (head->num != prev->num) {
            return 0;
        }
        head = head->next;
        prev = prev->next;
    }
    return 1;
}


void print(Lnode* L) {
    Lnode* p = L;
    while (p)
    {
        printf("%d", p->num);
        p = p->next;
    }
    printf("\n");
}

int main() {
    Lnode *L;
    L = createlink(5);
    print(L);
    printf("\n");
    printf("真假%d\n", isPalindrome(L));
    
    
    print(L);
}