sicily 1135 飞越原野 bfs

        这题因为两个地方打错变量，WA了好几次。

#include <iostream>

#include <queue>

#include <memory.h>

#define MAX 101



using namespace std;



struct status

{

	int x, y;

	int step;

	int remain_fly_step;

};



int dir_x[] = {0, 1, -1, 0};

int dir_y[] = {1, 0, 0, -1};



char my_map[MAX][MAX];

bool isvisit[MAX][MAX][MAX];

int d;

int m,n;



void bfs();

status fly(status, int , int );



int main()

{

	while (cin >> m >> n >> d)

	{

		for (int i = 0; i < m; i++)

			for (int j = 0; j < n; j++)

				cin >> my_map[i][j];



		memset(isvisit, false, sizeof(isvisit));

		bfs()

	}

	return 0;

}



void bfs()

{

	queue<status> Q;

	status tmp,p;

	p.x = 0;

	p.y = 0;

	p.remain_fly_step = d;

	p.step = 0;

	Q.push(p);

	isvisit[p.x][p.y][p.remain_fly_step] = true;



	while (!Q.empty())

	{

		p = Q.front();

		Q.pop();



		if (p.x == m-1 && p.y == n-1)

		{

			cout << p.step << endl;

			return ;

		}

		for (int i = 0; i < 4; i++)

		{

			tmp.x = p.x + dir_x[i];

			tmp.y = p.y + dir_y[i];

			tmp.remain_fly_step = p.remain_fly_step;

			tmp.step = p.step + 1;



			if (tmp.x >= 0 && tmp.x < m

			 && tmp.y >= 0 && tmp.y < n

			 && !isvisit[tmp.x][tmp.y][tmp.remain_fly_step]

			 && my_map[tmp.x][tmp.y] == 'P')

			{

				isvisit[tmp.x][tmp.y][tmp.remain_fly_step] = true;

				Q.push(tmp);

			}

		}



		for (int i = 0; i < 4; i++)

		{

			for (int j = 1; j <= p.remain_fly_step; j++)

			{

				tmp = fly(p, i, j);



				if (tmp.x >= 0 && tmp.x < m

					&&  tmp.y >= 0 && tmp.y < n

					&& !isvisit[tmp.x][tmp.y][tmp.remain_fly_step]

					&& my_map[tmp.x][tmp.y] == 'P'

					&& tmp.remain_fly_step >= 0)

					{

						Q.push(tmp);

						isvisit[tmp.x][tmp.y][tmp.remain_fly_step] = true;

					}

			}

		}

	}



	cout << "impossible" << endl;

}



status fly(status p, int mode, int step)

{

	status tmp;

	switch (mode)

	{

	case 0:

		tmp.x = p.x;

		tmp.y = p.y + step;

		tmp.step = p.step + 1;

		tmp.remain_fly_step = p.remain_fly_step - step;

		break;

	case 1:

		tmp.x = p.x;

		tmp.y = p.y - step;

		tmp.step = p.step + 1;

		tmp.remain_fly_step = p.remain_fly_step - step;

		break;

	case 2:

		tmp.x = p.x + step;

		tmp.y = p.y;

		tmp.step = p.step + 1;

		tmp.remain_fly_step = p.remain_fly_step - step;

		break;

	case 3:

		tmp.x = p.x - step;

		tmp.y = p.y;

		tmp.step = p.step + 1;

		tmp.remain_fly_step = p.remain_fly_step - step;

		break;

	}



	return tmp;

}