ZOJ_1091-Knight Moves

//이것은 내가 일찍이 할 줄 몰랐던 문제인데, 지금도 할 수 있다. 이에 기록한다//
AC 코드:

#include<stdio.h>
#include<string.h>
#define max 50
char a[max][max];
int vis[max][max];
int dir[8][2]={{2,1},{-2,1},{2,-1},{-2,-1},{1,2},{1,-2},{-1,2},{-1,-2}};
struct node
{
    int x,y,step;
}queue[max*max];
char s1[max];
char s2[max];
int x1,y1,x2,y2;
void bfs(int x,int y)
{
    struct node now,pre;
    queue[0].x=x1;
    queue[0].y=y1;
    queue[0].step=0;
    int e=0,h=1;
    while(e<h)
    {
        pre=queue[e];
        if(pre.x==x2&&pre.y==y2)
        {
            printf("%d knight moves.
",pre.step);
            return;
        }
        int i;
        for(i=0;i<8;i++)
        {
            now.x=pre.x+dir[i][0];
            now.y=pre.y+dir[i][1];
            now.step=pre.step+1;
            if(now.x>=1&&now.x<=8&&now.y>=1&&now.y<=8&&!vis[now.x][now.y])
            {
                vis[now.x][now.y]=1;
                queue[h++]=now;
            }
        }
        e++;
    }
}
int main()
{
    while(scanf("%s%s",s1,s2)!=EOF)
    {
        memset(vis,0,sizeof(vis));
        x1=s1[0]-'a'+1;
        y1=s1[1]-'0';
        x2=s2[0]-'a'+1;
        y2=s2[1]-'0';
        printf("To get from %s to %s takes ",s1,s2);
        bfs(x1,y1);
    }
    return 0;
}