ACM培训 Robot Motion

#include<stdio.h>
int move[4][2]={{0,1},{0,-1},{-1,0},{1,0}};
int turn(char w)
{
    if(w==‘N‘)
        return 2;
    if(w==‘E‘)
        return 0;
    if(w==‘S‘)
        return 3;
    return 1;
}
int main()
{
    char grid[100][100];
    int m,n,x,y,tx,ty,start_N;
    
    while(scanf("%d%d",&m,&n)!=EOF){
        int book[100][100]={0};
        if(m==0&&n==0)
            return 0;
        scanf("%d",&start_N);
        int step=0,loop,flag=0;
        for(int i=0;i<m;i++)
            scanf("%s",grid[i]);
        x=0,y=start_N-1;
        while(1){
            if(x==0&&y==start_N-1&&book[x][y]==0)
                book[x][y]=1;
            tx=x+move[turn(grid[x][y])][0];
            ty=y+move[turn(grid[x][y])][1];
            if(tx>=m||ty>=n||tx<0||ty<0){
                step=book[x][y];
                flag=1;
                break;
            }
            else if(book[tx][ty]!=0){
                step=book[tx][ty]-1;
                loop=book[x][y]-step;
                flag=2;
                break;
            }
            book[tx][ty]=book[x][y]+1;
            x=tx,y=ty;
        }
        if(flag==1)
            printf("%d step(s) to exit\n",step);
        else
            printf("%d step(s) before a loop of %d step(s)\n",step,loop);
    }
    return 0;
}