الحد الأدنى من الخطوات للوصول إلى الهدف بواسطة الفارس | مجموعة 2

الحد الأدنى من الخطوات للوصول إلى الهدف بواسطة الفارس | مجموعة 2

بالنظر إلى رقعة شطرنج مربعة بحجم N x N، يتم إعطاء موضع الفارس وموضع الهدف، وتتمثل المهمة في معرفة الحد الأدنى من الخطوات التي سيتخذها الفارس للوصول إلى موضع الهدف.
 

الحد الأدنى من الخطوات للوصول إلى الهدف بواسطة الفارس | مجموعة 2


أمثلة : 
 

Input : (2 4) - knight's position (6 4) - target cell Output : 2 Input : (4 5) (1 1) Output : 3 


 


لقد تمت بالفعل مناقشة نهج BFS لحل المشكلة المذكورة أعلاه في سابق بريد. في هذا المنشور تتم مناقشة حل البرمجة الديناميكية.
شرح المنهج :  
 

    الحالة 1 : إذا لم يكن الهدف على طول صف واحد أو عمود واحد من موضع الفارس. 
    دع رقعة الشطرنج مكونة من 8 × 8 خلية. الآن لنفترض أن الفارس عند (3 3) والهدف عند (7 8). هناك 8 حركات محتملة من الوضع الحالي للفارس، أي (2 1) (1 2) (4 1) (1 4) (5 2) (2 5) (5 4) (4 5). لكن من بين هذه الحركات فقط (5 4) و (4 5) ستكون نحو الهدف وكل ما عداها يذهب بعيداً عن الهدف. لذلك للعثور على الحد الأدنى من الخطوات، انتقل إلى (4 5) أو (5 4). الآن احسب الحد الأدنى من الخطوات المتخذة من (4 5) و (5 4) للوصول إلى الهدف. يتم حساب ذلك عن طريق البرمجة الديناميكية. وبالتالي ينتج عن ذلك الحد الأدنى من الخطوات من (3 3) إلى (7 8). الحالة 2 : إذا كان الهدف على طول صف واحد أو عمود واحد من موضع الفارس. 
    دع رقعة الشطرنج مكونة من 8 × 8 خلية. لنفترض الآن أن الفارس عند (4 3) والهدف عند (4 7). هناك 8 حركات محتملة ولكن نحو الهدف لا يوجد سوى 4 حركات أي (5 5) (3 5) (2 4) (6 4). حيث أن (5 5) يعادل (5 3) و(4 2) يعادل (4 6). إذن من هذه النقاط الأربع يمكن تحويلها إلى نقطتين. أخذ (5 5) و (6 4) (هنا). الآن احسب الحد الأدنى من الخطوات المتخذة من هاتين النقطتين للوصول إلى الهدف. يتم حساب ذلك عن طريق البرمجة الديناميكية. وبالتالي ينتج عن ذلك الحد الأدنى من الخطوات من (4 3) إلى (4 7).


استثناء : عندما يكون الفارس في الزاوية ويكون الهدف بحيث يكون الفرق بين إحداثيات x و y مع موضع الفارس هو (1 1) أو العكس. ثم الحد الأدنى من الخطوات سيكون 4.
معادلة البرمجة الديناميكية : 
 

1) موانئ دبي[diffOfX][diffOfY] هو الحد الأدنى من الخطوات المتخذة من موقع الفارس إلى موقع الهدف.
2) dp[diffOfX][diffOfY] = dp[diffOfY][diffOfX] .
حيث diffOfX = الفرق بين إحداثي x للفارس وإحداثي x للهدف 
diffOfY = الفرق بين إحداثي y للفارس وإحداثي y للهدف 
 


فيما يلي تنفيذ النهج أعلاه: 
 

C++
   // C++ code for minimum steps for   // a knight to reach target position   #include          using     namespace     std  ;   // initializing the matrix.   int     dp  [  8  ][  8  ]     =     {     0     };   int     getsteps  (  int     x       int     y           int     tx       int     ty  )   {      // if knight is on the target       // position return 0.      if     (  x     ==     tx     &&     y     ==     ty  )      return     dp  [  0  ][  0  ];      else     {          // if already calculated then return      // that value. Taking absolute difference.      if     (  dp  [  abs  (  x     -     tx  )][  abs  (  y     -     ty  )]     !=     0  )      return     dp  [  abs  (  x     -     tx  )][  abs  (  y     -     ty  )];          else     {      // there will be two distinct positions      // from the knight towards a target.      // if the target is in same row or column      // as of knight then there can be four      // positions towards the target but in that      // two would be the same and the other two      // would be the same.      int     x1       y1       x2       y2  ;          // (x1 y1) and (x2 y2) are two positions.      // these can be different according to situation.      // From position of knight the chess board can be      // divided into four blocks i.e.. N-E E-S S-W W-N .      if     (  x      <=     tx  )     {      if     (  y      <=     ty  )     {      x1     =     x     +     2  ;      y1     =     y     +     1  ;      x2     =     x     +     1  ;      y2     =     y     +     2  ;      }     else     {      x1     =     x     +     2  ;      y1     =     y     -     1  ;      x2     =     x     +     1  ;      y2     =     y     -     2  ;      }      }     else     {      if     (  y      <=     ty  )     {      x1     =     x     -     2  ;      y1     =     y     +     1  ;      x2     =     x     -     1  ;      y2     =     y     +     2  ;      }     else     {      x1     =     x     -     2  ;      y1     =     y     -     1  ;      x2     =     x     -     1  ;      y2     =     y     -     2  ;      }      }          // ans will be 1 + minimum of steps       // required from (x1 y1) and (x2 y2).      dp  [  abs  (  x     -     tx  )][  abs  (  y     -     ty  )]     =         min  (  getsteps  (  x1       y1       tx       ty  )         getsteps  (  x2       y2       tx       ty  ))     +     1  ;          // exchanging the coordinates x with y of both      // knight and target will result in same ans.      dp  [  abs  (  y     -     ty  )][  abs  (  x     -     tx  )]     =         dp  [  abs  (  x     -     tx  )][  abs  (  y     -     ty  )];      return     dp  [  abs  (  x     -     tx  )][  abs  (  y     -     ty  )];      }      }   }   // Driver Code   int     main  ()   {      int     i       n       x       y       tx       ty       ans  ;          // size of chess board n*n      n     =     100  ;          // (x y) coordinate of the knight.      // (tx ty) coordinate of the target position.      x     =     4  ;      y     =     5  ;      tx     =     1  ;      ty     =     1  ;      // (Exception) these are the four corner points       // for which the minimum steps is 4.      if     ((  x     ==     1     &&     y     ==     1     &&     tx     ==     2     &&     ty     ==     2  )     ||         (  x     ==     2     &&     y     ==     2     &&     tx     ==     1     &&     ty     ==     1  ))      ans     =     4  ;      else     if     ((  x     ==     1     &&     y     ==     n     &&     tx     ==     2     &&     ty     ==     n     -     1  )     ||      (  x     ==     2     &&     y     ==     n     -     1     &&     tx     ==     1     &&     ty     ==     n  ))      ans     =     4  ;      else     if     ((  x     ==     n     &&     y     ==     1     &&     tx     ==     n     -     1     &&     ty     ==     2  )     ||         (  x     ==     n     -     1     &&     y     ==     2     &&     tx     ==     n     &&     ty     ==     1  ))      ans     =     4  ;      else     if     ((  x     ==     n     &&     y     ==     n     &&     tx     ==     n     -     1     &&     ty     ==     n     -     1  )     ||         (  x     ==     n     -     1     &&     y     ==     n     -     1     &&     tx     ==     n     &&     ty     ==     n  ))      ans     =     4  ;      else     {      // dp[a][b] here a b is the difference of      // x & tx and y & ty respectively.      dp  [  1  ][  0  ]     =     3  ;      dp  [  0  ][  1  ]     =     3  ;      dp  [  1  ][  1  ]     =     2  ;      dp  [  2  ][  0  ]     =     2  ;      dp  [  0  ][  2  ]     =     2  ;      dp  [  2  ][  1  ]     =     1  ;      dp  [  1  ][  2  ]     =     1  ;      ans     =     getsteps  (  x       y       tx       ty  );      }      cout      < <     ans      < <     endl  ;      return     0  ;   }   
Java
   //Java code for minimum steps for    // a knight to reach target position    public     class   GFG     {   // initializing the matrix.       static     int     dp  [][]     =     new     int  [  8  ][  8  ]  ;      static     int     getsteps  (  int     x       int     y        int     tx       int     ty  )     {      // if knight is on the target       // position return 0.       if     (  x     ==     tx     &&     y     ==     ty  )     {      return     dp  [  0  ][  0  ]  ;      }     else     // if already calculated then return       // that value. Taking absolute difference.       if     (  dp  [     Math  .  abs  (  x     -     tx  )  ][     Math  .  abs  (  y     -     ty  )  ]     !=     0  )     {      return     dp  [     Math  .  abs  (  x     -     tx  )  ][     Math  .  abs  (  y     -     ty  )  ]  ;      }     else     {      // there will be two distinct positions       // from the knight towards a target.       // if the target is in same row or column       // as of knight then there can be four       // positions towards the target but in that       // two would be the same and the other two       // would be the same.       int     x1       y1       x2       y2  ;      // (x1 y1) and (x2 y2) are two positions.       // these can be different according to situation.       // From position of knight the chess board can be       // divided into four blocks i.e.. N-E E-S S-W W-N .       if     (  x      <=     tx  )     {      if     (  y      <=     ty  )     {      x1     =     x     +     2  ;      y1     =     y     +     1  ;      x2     =     x     +     1  ;      y2     =     y     +     2  ;      }     else     {      x1     =     x     +     2  ;      y1     =     y     -     1  ;      x2     =     x     +     1  ;      y2     =     y     -     2  ;      }      }     else     if     (  y      <=     ty  )     {      x1     =     x     -     2  ;      y1     =     y     +     1  ;      x2     =     x     -     1  ;      y2     =     y     +     2  ;      }     else     {      x1     =     x     -     2  ;      y1     =     y     -     1  ;      x2     =     x     -     1  ;      y2     =     y     -     2  ;      }      // ans will be 1 + minimum of steps       // required from (x1 y1) and (x2 y2).       dp  [     Math  .  abs  (  x     -     tx  )  ][     Math  .  abs  (  y     -     ty  )  ]      =     Math  .  min  (  getsteps  (  x1       y1       tx       ty  )      getsteps  (  x2       y2       tx       ty  ))     +     1  ;      // exchanging the coordinates x with y of both       // knight and target will result in same ans.       dp  [     Math  .  abs  (  y     -     ty  )  ][     Math  .  abs  (  x     -     tx  )  ]      =     dp  [     Math  .  abs  (  x     -     tx  )  ][     Math  .  abs  (  y     -     ty  )  ]  ;      return     dp  [     Math  .  abs  (  x     -     tx  )  ][     Math  .  abs  (  y     -     ty  )  ]  ;      }      }   // Driver Code       static     public     void     main  (  String  []     args  )     {      int     i       n       x       y       tx       ty       ans  ;      // size of chess board n*n       n     =     100  ;      // (x y) coordinate of the knight.       // (tx ty) coordinate of the target position.       x     =     4  ;      y     =     5  ;      tx     =     1  ;      ty     =     1  ;      // (Exception) these are the four corner points       // for which the minimum steps is 4.       if     ((  x     ==     1     &&     y     ==     1     &&     tx     ==     2     &&     ty     ==     2  )      ||     (  x     ==     2     &&     y     ==     2     &&     tx     ==     1     &&     ty     ==     1  ))     {      ans     =     4  ;      }     else     if     ((  x     ==     1     &&     y     ==     n     &&     tx     ==     2     &&     ty     ==     n     -     1  )      ||     (  x     ==     2     &&     y     ==     n     -     1     &&     tx     ==     1     &&     ty     ==     n  ))     {      ans     =     4  ;      }     else     if     ((  x     ==     n     &&     y     ==     1     &&     tx     ==     n     -     1     &&     ty     ==     2  )      ||     (  x     ==     n     -     1     &&     y     ==     2     &&     tx     ==     n     &&     ty     ==     1  ))     {      ans     =     4  ;      }     else     if     ((  x     ==     n     &&     y     ==     n     &&     tx     ==     n     -     1     &&     ty     ==     n     -     1  )      ||     (  x     ==     n     -     1     &&     y     ==     n     -     1     &&     tx     ==     n     &&     ty     ==     n  ))     {      ans     =     4  ;      }     else     {      // dp[a][b] here a b is the difference of       // x & tx and y & ty respectively.       dp  [  1  ][  0  ]     =     3  ;      dp  [  0  ][  1  ]     =     3  ;      dp  [  1  ][  1  ]     =     2  ;      dp  [  2  ][  0  ]     =     2  ;      dp  [  0  ][  2  ]     =     2  ;      dp  [  2  ][  1  ]     =     1  ;      dp  [  1  ][  2  ]     =     1  ;      ans     =     getsteps  (  x       y       tx       ty  );      }      System  .  out  .  println  (  ans  );      }   }   /*This code is contributed by PrinciRaj1992*/   
Python3
   # Python3 code for minimum steps for   # a knight to reach target position   # initializing the matrix.   dp   =   [[  0   for   i   in   range  (  8  )]   for   j   in   range  (  8  )];   def   getsteps  (  x     y     tx     ty  ):   # if knight is on the target   # position return 0.   if   (  x   ==   tx   and   y   ==   ty  ):   return   dp  [  0  ][  0  ];   # if already calculated then return   # that value. Taking absolute difference.   elif  (  dp  [  abs  (  x   -   tx  )][  abs  (  y   -   ty  )]   !=   0  ):   return   dp  [  abs  (  x   -   tx  )][  abs  (  y   -   ty  )];   else  :   # there will be two distinct positions   # from the knight towards a target.   # if the target is in same row or column   # as of knight then there can be four   # positions towards the target but in that   # two would be the same and the other two   # would be the same.   x1     y1     x2     y2   =   0     0     0     0  ;   # (x1 y1) and (x2 y2) are two positions.   # these can be different according to situation.   # From position of knight the chess board can be   # divided into four blocks i.e.. N-E E-S S-W W-N .   if   (  x    <=   tx  ):   if   (  y    <=   ty  ):   x1   =   x   +   2  ;   y1   =   y   +   1  ;   x2   =   x   +   1  ;   y2   =   y   +   2  ;   else  :   x1   =   x   +   2  ;   y1   =   y   -   1  ;   x2   =   x   +   1  ;   y2   =   y   -   2  ;   elif   (  y    <=   ty  ):   x1   =   x   -   2  ;   y1   =   y   +   1  ;   x2   =   x   -   1  ;   y2   =   y   +   2  ;   else  :   x1   =   x   -   2  ;   y1   =   y   -   1  ;   x2   =   x   -   1  ;   y2   =   y   -   2  ;   # ans will be 1 + minimum of steps   # required from (x1 y1) and (x2 y2).   dp  [  abs  (  x   -   tx  )][  abs  (  y   -   ty  )]   =    min  (  getsteps  (  x1     y1     tx     ty  )   getsteps  (  x2     y2     tx     ty  ))   +   1  ;   # exchanging the coordinates x with y of both   # knight and target will result in same ans.   dp  [  abs  (  y   -   ty  )][  abs  (  x   -   tx  )]   =    dp  [  abs  (  x   -   tx  )][  abs  (  y   -   ty  )];   return   dp  [  abs  (  x   -   tx  )][  abs  (  y   -   ty  )];   # Driver Code   if   __name__   ==   '__main__'  :   # size of chess board n*n   n   =   100  ;   # (x y) coordinate of the knight.   # (tx ty) coordinate of the target position.   x   =   4  ;   y   =   5  ;   tx   =   1  ;   ty   =   1  ;   # (Exception) these are the four corner points   # for which the minimum steps is 4.   if   ((  x   ==   1   and   y   ==   1   and   tx   ==   2   and   ty   ==   2  )   or   (  x   ==   2   and   y   ==   2   and   tx   ==   1   and   ty   ==   1  )):   ans   =   4  ;   elif   ((  x   ==   1   and   y   ==   n   and   tx   ==   2   and   ty   ==   n   -   1  )   or   (  x   ==   2   and   y   ==   n   -   1   and   tx   ==   1   and   ty   ==   n  )):   ans   =   4  ;   elif   ((  x   ==   n   and   y   ==   1   and   tx   ==   n   -   1   and   ty   ==   2  )   or   (  x   ==   n   -   1   and   y   ==   2   and   tx   ==   n   and   ty   ==   1  )):   ans   =   4  ;   elif   ((  x   ==   n   and   y   ==   n   and   tx   ==   n   -   1   and   ty   ==   n   -   1  )   or   (  x   ==   n   -   1   and   y   ==   n   -   1   and   tx   ==   n   and   ty   ==   n  )):   ans   =   4  ;   else  :   # dp[a][b] here a b is the difference of   # x & tx and y & ty respectively.   dp  [  1  ][  0  ]   =   3  ;   dp  [  0  ][  1  ]   =   3  ;   dp  [  1  ][  1  ]   =   2  ;   dp  [  2  ][  0  ]   =   2  ;   dp  [  0  ][  2  ]   =   2  ;   dp  [  2  ][  1  ]   =   1  ;   dp  [  1  ][  2  ]   =   1  ;   ans   =   getsteps  (  x     y     tx     ty  );   print  (  ans  );   # This code is contributed by PrinciRaj1992   
C#
   // C# code for minimum steps for    // a knight to reach target position    using     System  ;   public     class     GFG  {   // initializing the matrix.       static     int     [          ]  dp     =     new     int  [  8          8  ];         static     int     getsteps  (  int     x       int     y           int     tx       int     ty  )     {         // if knight is on the target       // position return 0.       if     (  x     ==     tx     &&     y     ==     ty  )     {         return     dp  [  0          0  ];         }     else     // if already calculated then return       // that value. Taking Absolute difference.       if     (  dp  [     Math  .     Abs  (  x     -     tx  )          Math  .     Abs  (  y     -     ty  )]     !=     0  )     {         return     dp  [     Math  .     Abs  (  x     -     tx  )          Math  .     Abs  (  y     -     ty  )];         }     else     {         // there will be two distinct positions       // from the knight towards a target.       // if the target is in same row or column       // as of knight then there can be four       // positions towards the target but in that       // two would be the same and the other two       // would be the same.       int     x1       y1       x2       y2  ;         // (x1 y1) and (x2 y2) are two positions.       // these can be different according to situation.       // From position of knight the chess board can be       // divided into four blocks i.e.. N-E E-S S-W W-N .       if     (  x      <=     tx  )     {         if     (  y      <=     ty  )     {         x1     =     x     +     2  ;         y1     =     y     +     1  ;         x2     =     x     +     1  ;         y2     =     y     +     2  ;         }     else     {         x1     =     x     +     2  ;         y1     =     y     -     1  ;         x2     =     x     +     1  ;         y2     =     y     -     2  ;         }         }     else     if     (  y      <=     ty  )     {         x1     =     x     -     2  ;         y1     =     y     +     1  ;         x2     =     x     -     1  ;         y2     =     y     +     2  ;         }     else     {         x1     =     x     -     2  ;         y1     =     y     -     1  ;         x2     =     x     -     1  ;         y2     =     y     -     2  ;         }         // ans will be 1 + minimum of steps       // required from (x1 y1) and (x2 y2).       dp  [     Math  .     Abs  (  x     -     tx  )          Math  .     Abs  (  y     -     ty  )]         =     Math  .  Min  (  getsteps  (  x1       y1       tx       ty  )         getsteps  (  x2       y2       tx       ty  ))     +     1  ;         // exchanging the coordinates x with y of both       // knight and target will result in same ans.       dp  [     Math  .     Abs  (  y     -     ty  )          Math  .     Abs  (  x     -     tx  )]         =     dp  [     Math  .     Abs  (  x     -     tx  )          Math  .     Abs  (  y     -     ty  )];         return     dp  [     Math  .     Abs  (  x     -     tx  )          Math  .     Abs  (  y     -     ty  )];         }         }      // Driver Code       static     public     void     Main  ()     {         int     i       n       x       y       tx       ty       ans  ;         // size of chess board n*n       n     =     100  ;         // (x y) coordinate of the knight.       // (tx ty) coordinate of the target position.       x     =     4  ;         y     =     5  ;         tx     =     1  ;         ty     =     1  ;         // (Exception) these are the four corner points       // for which the minimum steps is 4.       if     ((  x     ==     1     &&     y     ==     1     &&     tx     ==     2     &&     ty     ==     2  )         ||     (  x     ==     2     &&     y     ==     2     &&     tx     ==     1     &&     ty     ==     1  ))     {         ans     =     4  ;         }     else     if     ((  x     ==     1     &&     y     ==     n     &&     tx     ==     2     &&     ty     ==     n     -     1  )         ||     (  x     ==     2     &&     y     ==     n     -     1     &&     tx     ==     1     &&     ty     ==     n  ))     {         ans     =     4  ;         }     else     if     ((  x     ==     n     &&     y     ==     1     &&     tx     ==     n     -     1     &&     ty     ==     2  )         ||     (  x     ==     n     -     1     &&     y     ==     2     &&     tx     ==     n     &&     ty     ==     1  ))     {         ans     =     4  ;         }     else     if     ((  x     ==     n     &&     y     ==     n     &&     tx     ==     n     -     1     &&     ty     ==     n     -     1  )         ||     (  x     ==     n     -     1     &&     y     ==     n     -     1     &&     tx     ==     n     &&     ty     ==     n  ))     {         ans     =     4  ;         }     else     {         // dp[a  b] here a b is the difference of       // x & tx and y & ty respectively.       dp  [  1          0  ]     =     3  ;         dp  [  0          1  ]     =     3  ;         dp  [  1          1  ]     =     2  ;         dp  [  2          0  ]     =     2  ;         dp  [  0          2  ]     =     2  ;         dp  [  2          1  ]     =     1  ;         dp  [  1          2  ]     =     1  ;         ans     =     getsteps  (  x       y       tx       ty  );         }         Console  .  WriteLine  (  ans  );         }      }      /*This code is contributed by PrinciRaj1992*/   
JavaScript
    <  script  >   // JavaScript code for minimum steps for   // a knight to reach target position   // initializing the matrix.   let     dp     =     new     Array  (  8  )   for  (  let     i  =  0  ;  i   <  8  ;  i  ++  ){      dp  [  i  ]     =     new     Array  (  8  ).  fill  (  0  )   }   function     getsteps  (  x    y    tx    ty  )   {      // if knight is on the target      // position return 0.      if     (  x     ==     tx     &&     y     ==     ty  )      return     dp  [  0  ][  0  ];      else     {          // if already calculated then return      // that value. Taking absolute difference.      if     (  dp  [(  Math  .  abs  (  x     -     tx  ))][(  Math  .  abs  (  y     -     ty  ))]     !=     0  )      return     dp  [(  Math  .  abs  (  x     -     tx  ))][(  Math  .  abs  (  y     -     ty  ))];          else     {      // there will be two distinct positions      // from the knight towards a target.      // if the target is in same row or column      // as of knight then there can be four      // positions towards the target but in that      // two would be the same and the other two      // would be the same.      let     x1       y1       x2       y2  ;          // (x1 y1) and (x2 y2) are two positions.      // these can be different according to situation.      // From position of knight the chess board can be      // divided into four blocks i.e.. N-E E-S S-W W-N .      if     (  x      <=     tx  )     {      if     (  y      <=     ty  )     {      x1     =     x     +     2  ;      y1     =     y     +     1  ;      x2     =     x     +     1  ;      y2     =     y     +     2  ;      }     else     {      x1     =     x     +     2  ;      y1     =     y     -     1  ;      x2     =     x     +     1  ;      y2     =     y     -     2  ;      }      }     else     {      if     (  y      <=     ty  )     {      x1     =     x     -     2  ;      y1     =     y     +     1  ;      x2     =     x     -     1  ;      y2     =     y     +     2  ;      }     else     {      x1     =     x     -     2  ;      y1     =     y     -     1  ;      x2     =     x     -     1  ;      y2     =     y     -     2  ;      }      }          // ans will be 1 + minimum of steps      // required from (x1 y1) and (x2 y2).      dp  [(  Math  .  abs  (  x     -     tx  ))][(  Math  .  abs  (  y     -     ty  ))]     =      Math  .  min  (  getsteps  (  x1       y1       tx       ty  )      getsteps  (  x2       y2       tx       ty  ))     +     1  ;          // exchanging the coordinates x with y of both      // knight and target will result in same ans.      dp  [(  Math  .  abs  (  y     -     ty  ))][(  Math  .  abs  (  x     -     tx  ))]     =      dp  [(  Math  .  abs  (  x     -     tx  ))][(  Math  .  abs  (  y     -     ty  ))];      return     dp  [(  Math  .  abs  (  x     -     tx  ))][(  Math  .  abs  (  y     -     ty  ))];      }      }   }   // Driver Code   let     i       n       x       y       tx       ty       ans  ;   // size of chess board n*n   n     =     100  ;   // (x y) coordinate of the knight.   // (tx ty) coordinate of the target position.   x     =     4  ;   y     =     5  ;   tx     =     1  ;   ty     =     1  ;   // (Exception) these are the four corner points   // for which the minimum steps is 4.   if     ((  x     ==     1     &&     y     ==     1     &&     tx     ==     2     &&     ty     ==     2  )     ||   (  x     ==     2     &&     y     ==     2     &&     tx     ==     1     &&     ty     ==     1  ))      ans     =     4  ;   else     if     ((  x     ==     1     &&     y     ==     n     &&     tx     ==     2     &&     ty     ==     n     -     1  )     ||      (  x     ==     2     &&     y     ==     n     -     1     &&     tx     ==     1     &&     ty     ==     n  ))      ans     =     4  ;   else     if     ((  x     ==     n     &&     y     ==     1     &&     tx     ==     n     -     1     &&     ty     ==     2  )     ||      (  x     ==     n     -     1     &&     y     ==     2     &&     tx     ==     n     &&     ty     ==     1  ))      ans     =     4  ;   else     if     ((  x     ==     n     &&     y     ==     n     &&     tx     ==     n     -     1     &&     ty     ==     n     -     1  )     ||      (  x     ==     n     -     1     &&     y     ==     n     -     1     &&     tx     ==     n     &&     ty     ==     n  ))      ans     =     4  ;   else      {   // dp[a][b] here a b is the difference of   // x & tx and y & ty respectively.      dp  [  1  ][  0  ]     =     3  ;      dp  [  0  ][  1  ]     =     3  ;      dp  [  1  ][  1  ]     =     2  ;      dp  [  2  ][  0  ]     =     2  ;      dp  [  0  ][  2  ]     =     2  ;      dp  [  2  ][  1  ]     =     1  ;      dp  [  1  ][  2  ]     =     1  ;      ans     =     getsteps  (  x       y       tx       ty  );   }   document  .  write  (  ans    ' 
'
); // This code is contributed by shinjanpatra. < /script>

الإخراج:  
3 

 

تعقيد الوقت: O(N * M) حيث N هو إجمالي عدد الصفوف وM هو إجمالي عدد الأعمدة
المساحة المساعدة: يا (ن * م) 

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