题解 | #调整牛群顺序#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @param n int整型 
 * @return ListNode类
 */
struct ListNode* moveNthToEnd(struct ListNode* head, int n ) {
    // write code here
    int num = 0;
    struct ListNode* p = head;
    if(n == 1) return head;
    while(p != NULL){
        p =p->next;
        num++;
    }
    p = head;
    struct ListNode* q;
    if(n == num){
        q = head;
        head = head->next;
        p = p->next;
    }
    else{
        int i;
        for(i=1;i<num-n;i++){
            p = p->next;
        }
        q=p->next;
        p->next = q->next;   
    }
    q->next = NULL;
    while(p->next != NULL){
        p = p->next;
    }
    p->next = q;
    return head;
}