poj 2243 Knight Moves

一个8行8列的棋谱，任意给出knight的两个位子，问按照knight的走法，从其中的一个位子出发，问至少需要经过几步到达另外一个位子。 行用1-8表示，列用a-h表示,起始位置入队列，然后在当前结点能访问的结点依次搜索。。在进入队列前判断是否到达结束位置，用二维数组存储步数、、、、点击打开链接

#include<algorithm>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<vector> 
using namespace std;
typedef struct {
      int x;
      int y;
    }point;
vector<point> v;
int step[8][8];
point p;
bool ok;  //不知道为什么就是不让用find  
int index;  
int start_x, start_y, end_x, end_y;
int bfs(int x, int y, int time)  // time 每次记录当前的步数 
{
    if(x==end_x && y==end_y)
    {
      ok = true;
      return 0;
    }
    
    if(x-2>=0&&y-1>=0&&step[x-2][y-1]==-1)  //依次搜索 
    {
      step[x-2][y-1] = time+1;
      p.x = x-2;
      p.y = y-1;
      v.push_back(p);
    }
    
    if(x-1>=0&&y-2>=0&&step[x-1][y-2]==-1)
    {
      step[x-1][y-2] = time+1;
      p.x = x-1;
      p.y = y-2;
      v.push_back(p);
    }
    
    if(x-2>=0&&y+1<8&&step[x-2][y+1]==-1)
    {
      step[x-2][y+1] = time+1;
      p.x = x-2;
      p.y = y+1;
      v.push_back(p);
    }
    
    if(x-1>=0&&y+2<8&&step[x-1][y+2]==-1)
    {
      step[x-1][y+2] = time+1;
      p.x = x-1;
      p.y = y+2;
      v.push_back(p);
    }
    
    if(x+1<8&&y+2<8&&step[x+1][y+2]==-1)
    {
      step[x+1][y+2] = time+1;
      p.x = x+1;
      p.y = y+2;
      v.push_back(p);
    }
     
    if(x+2<8&&y+1<8&&step[x+2][y+1]==-1)
    {
      step[x+2][y+1] = time+1;
      p.x = x+2;
      p.y = y+1;
      v.push_back(p);
    }
    
    if(x+2<8&&y-1>=0&&step[x+2][y-1]==-1)
    {
      step[x+2][y-1] = time+1;
      p.x = x+2;
      p.y = y-1;
      v.push_back(p);
    }
    
    if(x+1<8&&y-2>=0&&step[x+1][y-2]==-1)
    {
      step[x+1][y-2] = time+1;
      p.x = x+1;
      p.y = y-2;
      v.push_back(p);
    }
}
int main()
{
    char s, e;
    int _s, _e;
    while(cin>>s>>_s>>e>>_e)
    {
    memset(step, -1, sizeof(step));
    start_x = (int)(s-'a'); 
    start_y = _s-1;
    end_x = (int)(e-'a');
    end_y = _e-1;
    p.x = start_x;
    p.y = start_y;
    v.clear(); 
    step[p.x][p.y]=0;
    v.push_back(p);
    ok = false;
    index = 0;
    while(!ok)
    {
      bfs(v[index].x, v[index].y, step[v[index].x][v[index].y]);   
      index++;
    }                       
    cout<<"To get from "<<s<<_s<<" to "<<e<<_e<<" takes "<<step[end_x][end_y]<<" knight moves."<<endl;
    }
   system("pause");
   return 0;
}