step1:
一些特殊情况先处理
作对称和交换满足 endy >= endx,staty >= statx
	if (startx > endx)
	{
		swap(startx, endx);
		swap(starty, endy);
	}
		if (starty > endy)
	{
		starty = n - 1 - starty;
		endy = n - 1 - endy;
	}
int linecheck(int n) //在某些些直线上预先排除
{
	minsteps = -1;
	int disy = endy - starty;
	int disx = endx - startx;
	if (disx == 0 && disy == 0)
		minsteps = 0;
	else if ( disy == 2 * disx || disx == 2 * disy)
		minsteps = disx < disy ? disx : disy;
	else if ( disx + disy == 1 )
		minsteps = 3;
	else if ( disx == 1 && disy == 1 && ( startx + starty == 0 || endx + endy == 2*(n -1) ) )
		minsteps = 4;
	else if (disx == 2 && disy == 2)
		minsteps = 4;
	return minsteps;
}

step2:

对于 n > 6
考虑奇偶性以及马每步跳的步长为3（2+1,1+2）
可以得到最小步 step3 >= { (disx + disx) / 3 }

int Search(int n)
{
	int step2, step3;
	int disx = endx - startx;
	int disy = endy - starty;

	step2 = disy > disx ? disy : disx ;
	if (step2 % 2 == 0)
		step2 /= 2;
	else
		step2 = step2 / 2 + 1;

	if ( (disx + disy) % 3 == 0 )
		step3 = (disx + disy) / 3;
	else
		step3 = (disx + disy) / 3 + 1;

	if (step3 < step2)
		step3 = step2;
	if ( step3 % 2 != (disx + disy) % 2 )
		step3 += 1;
	minsteps = step3;
	return step3;
}
step3
 对于n < 6 直接用BFS搜索

• Re:用一点数学方法加速 1915 (27) xh176233756 2007-01-17 20:23:12
  • 你是哪的？这方言好熟呀。。。。 (0) TopBoy 2007-01-17 22:45:11
    • Re:你是哪的？这方言好熟呀。。。。 (0) christbob 2007-04-20 00:21:30
  • 你是哪个学校的？我怎么不认识你？ (31) Sempr 2007-01-17 22:55:41
    • 你们还没考完呀，同情。。。。我们都放假啦，哈哈 (0) TopBoy 2007-01-17 23:03:54
      • 不是没考完，是还没开始考 -_____-!!! (0) Sempr 2007-01-17 23:08:30
  • 此人不是华工学生，鉴定完毕 (31) Trident 2007-01-18 11:54:30
  • 请xh176233756 修改个人信息 (31) Trident 2007-01-18 11:57:21
    • Do you know another 'hust' ;) (1) Judas 2007-01-18 20:32:45
      • harbin university of science and technology? (5) wywcgs 2007-01-18 20:36:23
        • 对, 应该还有. (0) Judas 2007-01-18 20:56:07
  • 1915 (13) xh176233756 2007-02-12 12:05:37
    • Re:呵呵 (17) sweller 2007-02-12 12:39:05
• Re:强，赞一个，同时bs楼上 (1386) sweller 2007-01-17 22:32:15
  • Re:强，赞一个，同时bs楼上 (12) xh176233756 2007-01-28 10:43:46
• Re:用一点数学方法加速 1915 (12) xmu_hunters 2007-07-06 13:22:21
• Re:用一点数学方法加速 1915 (1386) 102899 2008-05-19 20:00:50