hdu 1030

本題我用的方法是模擬.

#include <iostream>
#include <math.h>

inline int GetLine(int m)
{
	double sqrtm = sqrt((long double)m);
	if ((sqrtm - (int)sqrtm) > 0)
	{
		return (int)sqrtm + 1;
	}
	else
	{
		return (int)sqrtm;
	}
}

inline bool UpInLine(int m)
{
	// Get line number of m
	int line = GetLine(m);
	
	if (line % 2 != 0)
	{
		// if line is odd, odd down, even up
		return (m % 2 == 0) ? true : false;
	}
	else
	{
		// if line is even, odd up, even down
		return (m % 2 == 0) ? false : true;
	}
}

inline bool SameLine(int m, int n)
{
	return GetLine(m) == GetLine(n);
}

// is m is left to n
inline bool DirectLeft(int m, int n)
{
	// Move m to the line same as n
	int linem = GetLine(m);
	int linen = GetLine(n);
	int movem = m;
	while (linem < linen)
	{
		movem += 2 * linem;
		linem++;
	}

	return (movem < n) ? true : false;
}

inline int MoveDown(int m)
{
	return m + 2 * GetLine(m);
}

inline int MoveLeft(int m)
{
	return m - 1;
}

inline int MoveRight(int m)
{
	return m + 1;
}

int main()
{
	int m, n;

	while (std::cin >> m >> n)
	{
		// let m < n
		if (m > n)
		{
			int tmp = m;
			m = n;
			n = tmp;
		}

		int count = 0;

		// up to down
		while (m != n)
		{
			if (GetLine(m) != GetLine(n))
			{
				// if m, n is not in the same line
				if (UpInLine(m))
				{
					// if m is up in its line, move left or right, by it's direct to n
					if (DirectLeft(m, n))
					{
						// Move Right
						m = MoveRight(m);
					}
					else
					{
						m = MoveLeft(m);
					}
				}
				else
				{
					// if m is down in its line, move down
					m = MoveDown(m);
				}
			}
			else
			{
				// if m, n is in the same line
				// direct move m left or right by it's direct to n
				if (DirectLeft(m, n))
				{
					m = MoveRight(m);
				}
				else
				{
					m = MoveLeft(m);
				}
			}

			count++;
		}

		printf("%d\n", count);
	}

	return 0;
}