poj1573 Robot Motion

题目大意：一个机器人进入标记东西南北的图，判断是否能够走出来。

题目分析：机器人可能走出来，也可能在图中进入死循环，所以要定义一个数组标记该点是否走过。

题目代码：

#include <iostream>
//#include <string.h>
 using namespace std;

 int main ()
 {
    introw,col,start;
    inti,j;

    intstep;
    intnum;
    charmap[100][100];         
    boolvisit[100][100];
   while(cin>>row>>col>>start)
    {
      if(row==0 && col==0&& start==0)
      break;

      for(i=1;i<=row;i++)
         for(j=1;j<=col;j++)
         cin>>map[i][j];

         i=1;
         step=0;
         num=0;
         memset(visit,false,sizeof(visit));

      while(i>=1 &&i<=row &&start>=1 &&start<=col &&!visit[i][start])
         {

             if(map[i][start]=='W' )
             {
                  visit[i][start]=true;
                  start--;
                  step++;

                  continue;
             }
              if(map[i][start]=='E')
             {
                 visit[i][start]=true;
                  start++;
                  step++;

                  continue;
             }
              if(map[i][start]=='N')
             {
                  visit[i][start]=true;
                  i--;
                  step++;
                  continue;
             }
              if(map[i][start]=='S')
             {
                  visit[i][start]=true;
                  i++;
                  step++;
                  continue;
             }

         }

 

       if(visit[i][start])//如果是因为走到已经走过的点而退出，则从该点开始继续前进求出循环的num
         {
             memset(visit,false,sizeof(visit));

            while(i>=1 &&i<=row &&start>=1 &&start<=col &&!visit[i][start])
         {

             if(map[i][start]=='W' )
             {
                  visit[i][start]=true;
                  start--;
                  num++;

                  continue;
             }
              if(map[i][start]=='E')
             {
                 visit[i][start]=true;
                  start++;
                  num++;

                  continue;
             }
              if(map[i][start]=='N')
             {
                  visit[i][start]=true;
                  i--;
                  num++;
                  continue;
             }
              if(map[i][start]=='S')
             {
                  visit[i][start]=true;
                  i++;
                  num++;
                  continue;
             }

         }
         cout<<step-num<<"step(s) before a loop of"<<num<<"step(s)"<<endl;

       }

     else      //机器人走出来的话，直接输出step
        cout<<step<<"step(s) to exit"<<endl;
    }

   return 0;
 }