題意:有一條杆，長度為L，上面很幾隻螞蟻,螞蟻的朝向未知,爬速1cm/s,在爬行過程中,螞蟻相撞了就往反方向爬,問,杆上沒有螞蟻至少要多久,至多要多久

解題思路:

螞蟻1和螞蟻2相撞，我們只要交換一下1和2的編號就可以,相當於沒碰撞.

#include "pch.h"
#include <string>
#include<iostream>
#include<map>
#include<memory.h>
#include<vector>
#include<algorithm>
#include<queue>
#include<vector>


namespace cc
{
	using std::cout;
	using std::endl;
	using std::cin;
	using std::map;
	using std::vector;
	using std::string;
	using std::sort;
	using std::priority_queue;
	using std::greater;
	using std::vector;

	constexpr int N = 5000;

	//priority_queue<int,vector<int>, greater<int> >q;


	void solve()
	{
		int n;
		cin >> n;
		while (n--)
		{

			auto MAX = INT32_MIN;
			auto MIN = INT32_MAX;
			int m1, m2, m;
			int L;
			cin >> L;
			if (L % 2 == 0)
				m1 = m2 = L / 2;
			else
			{
				m1 = L / 2;
				m2 = (L + 1) / 2;
			}
			int total, k;
			cin >> total;
			for (int i = 0;i < total;++i)
			{
				cin >> k;
				//max
				if (k > MAX)
					MAX = k;
				if (L - k > MAX)
					MAX = L - k;
				//min,離中點最近的點,
				if (k <= m1)
				{
					if (MIN > m1 - k)
					{
						MIN = m1 - k;
						m = k;
					}
				}
				else if (k >= m2)
				{
					if (MIN > k - m2)
					{
						MIN = k - m2;
						m = k;
					}
				}
			}
			m = m < L - m ? m : L - m;
			cout << m << " " << MAX << endl;

		}
	}

};


int main()
{

#ifndef ONLINE_JUDGE
	freopen("d://1.text", "r", stdin);
#endif // !ONLINE_JUDGE
	cc::solve();

	return 0;
}