29.删除倒数第N个节点

1.直接看代码吧

思路在代码注释前边很简单的题

struct ListNode* removeNthFromEnd(struct ListNode* head, int n) {
    if(head == NULL){
        return NULL;
    }
    struct ListNode* dummy = (struct ListNode*)malloc(sizeof(struct ListNode));
    dummy->next = head;
    struct ListNode* pre = dummy;
    while(n>0){
        head = head->next;
        n--;
    }
    while(head!=NULL){
        pre = pre->next;
        head =  head->next;
    }
    pre->next = pre->next->next;
    return dummy->next;
}