[leetcode]移除链表尾端第n个结点

Given a linked list, remove the n-th node from the end of list and return its head.
给定链接列表，从列表末尾删除第n个节点并返回其头部。

一.c++代码

#include <iostream>
    using namespace  std; 
    //Definition for singly-linked list.
     struct ListNode {
        int val;
         ListNode *next;
         ListNode(int x) : val(x), next(NULL) {}
     };

    class Solution {
    public:
        ListNode* removeNthFromEnd(ListNode* head, int n) {
            int length1=1;
            ListNode* p = head;
            ListNode* q = head;
		
		while (p->next)
		{
			length1++;
			p = p->next;

		}
		int cha = length1 - n;
		//if (length1 == 1)
		//	return NULL;

		if (length1 <= n)
			head = head->next;
		else
		{
			for (int i = 0; i < (cha - 1); i++)
			{
				q = q->next;
			}
			ListNode *t = q->next;
			q->next = t->next;
			delete t;
		}
		return head; 
	}
};

测试结果

int main() {

	/*Solution *s;*/
	ListNode* l1 = new ListNode(1);
	ListNode *l11 = l1;
	l11->next = new ListNode(2);
	l11 = l11->next;
	l11->next = new ListNode(3);
	l11 = l11->next;
	l11->next = new ListNode(4);
	l11 = l11->next;
	l11->next = new ListNode(5);
	Solution* s = new Solution;
	s->removeNthFromEnd(l1, 1);
	system("pause");
	return 0;
}