hdu 1372 ( Knight Moves ) BFS

/*不停地BFS 我发现BFS的题目泛滥了*/

Problem : 1372 ( Knight Moves )     Judge Status : Accepted
RunId : 3710302    Language : C++    Author : zjut11018
Code Render Status : Rendered By HDOJ C++ Code Render Version 0.01 Beta
#include<iostream>
#include<queue>
#include<string>
using namespace std;
int dir[8][2]={-1,-2,-1,2,-2,1,-2,-1,2,1,2,-1,1,2,1,-2};
int vis[8][8],ans;
struct node
{
    int x,y,dis;
    node(int _x=0,int _y=0,int _dis=0):x(_x),y(_y),dis(_dis){};
};
node s,e;
string a[2];
void BFS()
{
    memset(vis,0,sizeof(vis));
    queue <node> q;
    q.push(s);
    vis[s.x][s.y]=1;
    while(!q.empty())
    {
        node t=q.front();
        q.pop();
        if(e.x==t.x&&e.y==t.y){ans=t.dis;return;}
        for(int k=0;k<8;k++)
        {
            int x=t.x+dir[k][0];
            int y=t.y+dir[k][1];
            if(x>=0&&x<8&&y>=0&&y<8&&!vis[x][y])
            {
                vis[x][y]=1;
                q.push(node(x,y,t.dis+1));
            }

        }

    }
}
int main()
{
    while(cin>>a[0]>>a[1])
    {
        s.x=a[0][0]-'a';s.y=a[0][1]-'1';s.dis=0;
        e.x=a[1][0]-'a';e.y=a[1][1]-'1';
        ans=0;
        BFS();
        cout<<"To get from "<<a[0]<<" to "<<a[1]<<" takes "<<ans<<" knight moves."<<endl;
    }
}