hd 1885 Key Task

#include <iostream>
#include <queue>
using namespace std;
const int MAX = 101;
typedef struct  
{
    int x, y;
    int cnt;
    int key;
}Node;
char Map[MAX][MAX];
int m, n;
int dir[4][2] = {{0,1},{0,-1},{1,0},{-1,0}};
bool state[MAX][MAX][16];
int c_state(char c)
{
    if( c=='B'||c=='b' ) return 1;
    if( c=='Y'||c=='y' ) return 2;
    if( c=='R'||c=='r' ) return 4;
    if( c=='G'||c=='g' ) return 8;
} 
int main()
{
    int i, j, k;
    int x, y, key;
    Node sn, tn, ttn;
    queue<Node> mq;
    while (scanf("%d%d", &m, &n) != EOF)
    {
        getchar();
        if(m==0 && n==0)
            break;
        for (i=0; i<m; ++i)
        {
            for (j=0; j<n; ++j)
            {
                scanf("%c", &Map[i][j]);
                if(Map[i][j] == '*')
                {
                    sn.x = i, sn.y = j, sn.cnt = 0, sn.key = 0;
                }
            }
            getchar();
        }
        bool flag = false;
        memset(state, false, sizeof(state));
        state[sn.x][sn.y][0] = true;

        mq.push(sn);
        while (!mq.empty())
        {
            tn = mq.front();
            mq.pop();
            if(Map[tn.x][tn.y] == 'X')
            {
                flag = true;
                break;
            }
            for(i=0; i<4; ++i)
            {
                x = tn.x + dir[i][0];
                y = tn.y + dir[i][1];
                if(x>=0&&x<m && y>=0&&y<n && Map[x][y]!='#')
                {
                    if(Map[x][y]=='B'||Map[x][y]=='Y'||Map[x][y]=='R'||Map[x][y]=='G')
                    {
                        k = c_state(Map[x][y]);
                        if( !(k&tn.key) ) continue;
                        key =tn.key;
                    }
                    else if(Map[x][y]=='b'||Map[x][y]=='y'||Map[x][y]=='r'||Map[x][y]=='g')
                    {
                        k = c_state(Map[x][y]);
                        key = k|tn.key;
                    }
                    else
                        key = tn.key;
                    if(!state[x][y][key])
                    {
                        state[x][y][key] = true;
                        ttn.x = x;
                        ttn.y = y;
                        ttn.key = key;
                        ttn.cnt = tn.cnt+1;
                        mq.push(ttn);
                    }
                }
            }
        }
        while(!mq.empty())
            mq.pop();
        if(flag)
            printf("Escape possible in %d steps./n",tn.cnt);
        else
            printf("The poor student is trapped!/n");
        
    }
    return 0;
}