删除链表的倒数第N个节点

/*
最长回文字串。
*/
#include<stdio.h>
#include<malloc.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#include <iostream>
typedef struct ListNode{
    int val;
    struct ListNode *next;
};
void print(struct ListNode *L){
    struct ListNode *p=L->next;
    while(p){
        printf("%d ",p->val);
        p=p->next;
    }
    printf("
");
}
void create(struct ListNode *&L,int a[],int n){
    struct ListNode *r,*s;
    L=(struct ListNode*)malloc(sizeof(struct ListNode));
    r=L;
    int i;
    for(i=0;i<n;i++){
        s=(struct ListNode*)malloc(sizeof(struct ListNode));
        s->val=a[i];
        r->next=s;
        r=s;
    }
    r->next=NULL;
}

struct ListNode* removeNthFromEnd(struct ListNode* head, int n){
    struct ListNode* p,*q;
    p=q=head;
    if(!head||!head->next)
        return NULL;
    while(n){
        q=q->next;
        n--;
    }
    if(!q) return p->next;
    q=q->next;
    while(q){
        p=p->next;
        q=q->next;
    }
    p->next=p->next->next;
    return head;
}

int main()
{
    int n=2,a[n]={1,2};
    struct ListNode *L;
    create(L,a,n);
    print(L);
    removeNthFromEnd(L,2);
    print(L);
    return 0;
}