poj 2251 Dungeon Master

#include <iostream>
#include <queue>
using namespace std;
const int MAXSIZE = 300;
struct coord {
int x, y, z;
int step;
bool operator()(const coord &a, const coord &b)
{
return a.step > b.step;
}
};
char map[MAXSIZE][MAXSIZE][MAXSIZE];
int direct[6][3] = {1,0,0,-1,0,0,0,1,0,0,-1,0,0,0,-1,0,0,1};
int main()
{
int i, j, k;
while (true)
{
int a, b, c;
coord start;
int sum;
priority_queue<coord, vector<coord>, coord> s;
cin >> i >> j >> k;
if (i == 0 && j == 0 && k == 0)
break;
for (c = 1; c <= i; c++)
for (a = 1; a <= j; a++)
for (b = 1; b <= k; b++)
{
cin >> map[c][a][b];
if (map[c][a][b] == 'S')
{
start.z = c;
start.x = a;
start.y = b;
start.step = 0;
}
}
s.push(start);
map[start.z][start.x][start.y] = '#';
bool flag = false;
while (!s.empty())
{
coord kk = s.top();
s.pop();
for (int b = 0; b < 6; b++)
{
start.z = kk.z + direct[b][0];
start.x = kk.x + direct[b][1];
start.y = kk.y + direct[b][2];
if (start.z >= 1 && start.x >= 1 && start.z >= 1 && start.z <= i&&start.x <= j&&start.y <= k)
{
if (map[start.z][start.x][start.y] == '.')
{
start.step = kk.step + 1;
s.push(start);
map[start.z][start.x][start.y] = '#';
}
else if (map[start.z][start.x][start.y] == 'E')
{
flag = true;
sum = kk.step + 1;
break;
}
}
}
if (flag)
break;
}
if (flag)
cout << "Escaped in " << sum << " minute(s)." << endl;
else
cout << "Trapped!" << endl;
}
}