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;
}