广度搜素，用链表写的，代码很差，时间也很慢。不知道还有什么好方法，貌似是有的，有人用0ms过了。

#include <iostream>
int chess[301][301]={0};
using namespace std;
typedef struct bound
{
        int x;
        int y;
        int count;
        struct bound *next;
        }Set;
int main()
{
    int n;
    cin >>n;
    while(n--)
    {
              int line;
              int sx,sy;
              int dx,dy;
              cin >>line>>sx>>sy>>dx>>dy;
              Set *f,*r,*t;
              t=new Set;
              f=t;
              r=t;
              t->x=sx;
              t->y=sy;
              t->count=0;
              chess[sx][sy]=-1;
              for(int i=0;i<line;i++)
      for(int j=0;j<line;j++)
       chess[i][j]=0;
     if(dx==sx&&dy==sy)
     {
      cout<<"0"<<endl;
     }
     else
     {
              while(1)
              {
                                       if(f->x-2>=0&&f->y+1<=(line-1)&&chess[f->x-2][f->y+1]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x-2;
                                                               t->y=f->y+1;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                       if(f->x-1>=0&&f->y+2<=(line-1)&&chess[f->x-1][f->y+2]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x-1;
                                                               t->y=f->y+2;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                       if(f->x+1<=(line-1)&&f->y+2<=(line-1)&&chess[f->x+1][f->y+2]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x+1;
                                                               t->y=f->y+2;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                       if(f->x+2<=(line-1)&&f->y+1<=(line-1)&&chess[f->x+2][f->y+1]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x+2;
                                                               t->y=f->y+1;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                       if(f->x+2<=(line-1)&&f->y-1>=0&&chess[f->x+2][f->y-1]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x+2;
                                                               t->y=f->y-1;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                       if(f->x+1<=(line-1)&&f->y-2>=0&&chess[f->x+1][f->y-2]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x+1;
                                                               t->y=f->y-2;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                        if(f->x-1>=0&&f->y-2>=0&&chess[f->x-1][f->y-2]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x-1;
                                                               t->y=f->y-2;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
                                                               }
                                       if(f->x-2>=0&&f->y-1>=0&&chess[f->x-2][f->y-1]==0)
                                       {
                                                               t=new Set;
                                                               t->x=f->x-2;
                                                               t->y=f->y-1;
                                                               t->count=f->count+1;
                                                               r->next=t;
                                                               r=t;
                                                               chess[t->x][t->y]=-1;
                  if(t->x==dx&&t->y==dy)
                  {
                   cout<<t->count<<endl;
                   break;
                  }
            }
                                       t=f;
                                       f=f->next;
                                       delete t;                                       
                      }
                     // cout<<f->count<<endl;
              }
  }
              return 0;
}