/** \brief poj 1573
 *
 * \param date 2014/8/5
 * \param state
 * \return memory 744k time 0ms
 *
 */

#include <iostream>
#include <fstream>
#include <cstring>
#include <queue>

using namespace std;

const int MAXN=11;
int Map[MAXN][MAXN];
//int vis[MAXN][MAXN];
int DirX[4]={0,1,0,-1};
int DirY[4]={1,0,-1,0};

int rows,columns;
queue<int> q;
struct P
{
    int x,y;
};
P points[110];
int flag;

int BFS()
{
    int nStep;

    while(!q.empty())
    {
        nStep=q.front();
        q.pop();
        for(int i=0;i<=nStep;i++)
        {
            points[i].x=q.front();
            q.pop();
            points[i].y=q.front();
            q.pop();
        }

        if(points[nStep].x<0 || points[nStep].x>=rows
           || points[nStep].y<0 || points[nStep].y>=columns)
            return nStep;

        for(int i=0;i<=nStep;i++)
        {
            if(i<nStep && points[nStep].x==points[i].x
               && points[nStep].y==points[i].y)
            {
                flag=i;
                return nStep-i;
            }
        }

        q.push(nStep+1);
        for(int i=0;i<=nStep;i++)
        {
            q.push(points[i].x);
            q.push(points[i].y);
        }
        int nDir=Map[points[nStep].x][points[nStep].y];

        q.push(points[nStep].x+DirX[nDir-1]);
        q.push(points[nStep].y+DirY[nDir-1]);

    }

}

void OutputMap()
{
    for(int i=0;i<rows;i++)
    {
        for(int j=0;j<columns;j++)
        {
            cout<<Map[i][j];
        }
        cout<<endl;
    }
}

int main()
{
    //cout << "Hello world!" << endl;
    //freopen("input.txt","r",stdin);
    int x,y;
    while(cin>>rows>>columns>>y)
    {
        while(!q.empty())
            q.pop();
        flag=-1;
        if(rows==0 && columns==0 && y==0)break;
        memset(Map,0,sizeof(Map));
        //memset(vis,0,sizeof(vis));
        x=0;
        char dir;
        for(int i=0;i<rows;i++)
        {
            for(int j=0;j<columns;j++)
            {
                cin>>dir;
                switch(dir)
                {
                case 'E':
                    Map[i][j]=1;
                    break;
                case 'S':
                    Map[i][j]=2;
                    break;
                case 'W':
                    Map[i][j]=3;
                    break;
                case 'N':
                    Map[i][j]=4;
                }
            }
        }
        //OutputMap();
        int step=0;
        q.push(step);
        q.push(x);
        q.push(y-1);
        //vis[x][y-1]=1;
        step=BFS();
        if(flag==-1)
            cout<<step<<" step(s) to exit"<<endl;
        else
            cout<<flag<<" step(s) before a loop of "<<step<<" step(s)"<<endl;
    }
    return 0;
}

注意二维数组的变化

[0][0], [0][1], [0][2].....[0][m-1]

[1][0], [1][1], [1][2].....[1][m-1]

[2][0], ......

...

[n-1][0],  [n-1][1] ... ....  [n-1][m-1]