Bruņinieka varbūtība palikt šaha galdiņā

Bruņinieka varbūtība palikt šaha galdiņā
Izmēģiniet to GfG Practice

Ņemot vērā a n*n šaha galds un bruņinieks pozīciju (x y) katru reizi, kad bruņinieks ir jāpārvieto, tas izvēlas vienu no astoņiem iespējamiem gājieniem vienādi nejauši (pat ja figūra nokristu no šaha dēļa) un kustas tur. Bruņinieks turpinās pārvietojas, līdz tas ir izdarījis precīzi k kustas vai ir pārcēlās prom šaha galds. Uzdevums ir atrast uz varbūtība ka bruņinieks paliek uz dēlis pēc tam, kad tā ir bijusi apstājās pārvietojas.

Piezīme: Šaha bruņinieks var izdarīt astoņus iespējamos gājienus. Katra kustība ir divas šūnas kardinālā virzienā, pēc tam viena šūna ortogonālā virzienā.

Piemēri:  

Ievade: n = 8 x = 0 y = 0 k = 1
Izvade: 0.25
Paskaidrojums: Bruņinieks sāk no (0 0) un pēc viena soļa speršanas gulēs galda iekšpusē tikai 2 no 8 pozīcijām, kas ir (1 2) un (2 1). Tādējādi varbūtība būs 2/8 = 0,25.

Ievade: n = 8 x = 0 y = 0 k = 3
Izvade: 0,125

Ievade: n = 4 x = 1 y = 2 k = 4
Izvade: 0,024414

Satura rādītājs

No augšas uz leju Dp izmantošana (atgādināšana) — O(n*n*k) laiks un O(n*n*k) telpa

Varbūtība, ka bruņinieks paliks šaha galdiņā pēc k gājienu, ir vienāda ar vidējo bruņinieka iespējamību iepriekšējās astoņās pozīcijās pēc k - 1 gājiena. Tāpat varbūtība pēc k-1 gājieniem ir atkarīga no vidējās varbūtības pēc k-2 gājieniem. Ideja ir izmantot iegaumēšana lai saglabātu iepriekšējo gājienu varbūtības un atrastu to vidējo, lai aprēķinātu gala rezultātu.
Lai to izdarītu, izveidojiet a 3D masīva piezīme[][][] kur piezīme[i][j][k] saglabā varbūtību, ka bruņinieks būs šūnā (i j) pēc k pārvietošanās. Ja k ir nulle, t.i., ir sasniegts sākuma stāvoklis atgriešanās 1 citādi izpētiet iepriekšējās astoņas pozīcijas un atrodiet to varbūtību vidējo vērtību.

C++
   // C++ program to find the probability of the   // knight to remain inside the chessboard   #include          using     namespace     std  ;   // recursive function to calculate   // knight probability   double     knightProbability  (  int     n       int     x       int     y       int     k           vector   <  vector   <  vector   <  double  >>>     &  memo  ){      // Base case initial probability      if  (  k     ==     0  )     return     1.0  ;      // check if already calculated      if  (  memo  [  x  ][  y  ][  k  ]     !=     -1  )     return     memo  [  x  ][  y  ][  k  ];      vector   <  vector   <  int  >>     directions     =     {{  1       2  }     {  2       1  }     {  2       -1  }      {  1       -2  }     {  -1       -2  }     {  -2       -1  }     {  -2       1  }     {  -1       2  }};      memo  [  x  ][  y  ][  k  ]     =     0  ;      double     cur     =     0.0  ;      // for every position reachable from (xy)      for  (  auto     d  :  directions  ){      int     u     =     x     +     d  [  0  ];      int     v     =     y     +     d  [  1  ];      // if this position lie inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     knightProbability  (  n       u       v       k  -1       memo  )     /     8.0  ;      }      return     memo  [  x  ][  y  ][  k  ]     =     cur  ;   }   // Function to find the probability   double     findProb  (  int     n       int     x       int     y       int     k  )     {      // Initialize memo to store results      vector   <  vector   <  vector   <  double  >>>     memo  (  n           vector   <  vector   <  double  >>  (  n        vector   <  double  >     (  k  +  1       -1  )));      return     knightProbability  (  n       x       y       k       memo  );   }   int     main  (){      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      cout      < <     findProb  (  n       x       y       k  )      < <     endl  ;      return     0  ;   }   
Java
   // Java program to find the probability of the   // knight to remain inside the chessboard   class   GfG     {      // recursive function to calculate      // knight probability      static     double     knightProbability  (  int     n       int     x           int     y       int     k       double  [][][]     memo  )     {      // Base case initial probability      if     (  k     ==     0  )     return     1.0  ;      // check if already calculated      if     (  memo  [  x  ][  y  ][  k  ]     !=     -  1  )     return     memo  [  x  ][  y  ][  k  ]  ;      int  [][]     directions     =     {{  1       2  }     {  2       1  }     {  2       -  1  }     {  1       -  2  }      {  -  1       -  2  }     {  -  2       -  1  }     {  -  2       1  }     {  -  1       2  }};      memo  [  x  ][  y  ][  k  ]     =     0  ;      double     cur     =     0.0  ;      // for every position reachable from (x y)      for     (  int  []     d     :     directions  )     {      int     u     =     x     +     d  [  0  ]  ;      int     v     =     y     +     d  [  1  ]  ;      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     knightProbability  (  n       u       v       k     -     1       memo  )     /     8.0  ;      }      return     memo  [  x  ][  y  ][  k  ]     =     cur  ;      }      // Function to find the probability      static     double     findProb  (  int     n       int     x       int     y       int     k  )     {      // Initialize memo to store results      double  [][][]     memo     =     new     double  [  n  ][  n  ][  k     +     1  ]  ;      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  int     j     =     0  ;     j      <     n  ;     j  ++  )     {      for     (  int     m     =     0  ;     m      <=     k  ;     m  ++  )     {      memo  [  i  ][  j  ][  m  ]     =     -  1  ;      }      }      }      return     knightProbability  (  n       x       y       k       memo  );      }      public     static     void     main  (  String  []     args  )     {      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      System  .  out  .  println  (  findProb  (  n       x       y       k  ));      }   }   
Python
   # Python program to find the probability of the   # knight to remain inside the chessboard   # recursive function to calculate   # knight probability   def   knightProbability  (  n     x     y     k     memo  ):   # Base case initial probability   if   k   ==   0  :   return   1.0   # check if already calculated   if   memo  [  x  ][  y  ][  k  ]   !=   -  1  :   return   memo  [  x  ][  y  ][  k  ]   directions   =   [   [  1     2  ]   [  2     1  ]   [  2     -  1  ]   [  1     -  2  ]   [  -  1     -  2  ]   [  -  2     -  1  ]   [  -  2     1  ]   [  -  1     2  ]   ]   memo  [  x  ][  y  ][  k  ]   =   0   cur   =   0.0   # for every position reachable from (x y)   for   d   in   directions  :   u   =   x   +   d  [  0  ]   v   =   y   +   d  [  1  ]   # if this position lies inside the board   if   0    <=   u    <   n   and   0    <=   v    <   n  :   cur   +=   knightProbability  (  n     u     v     k   -   1     memo  )   /   8.0   memo  [  x  ][  y  ][  k  ]   =   cur   return   cur   # Function to find the probability   def   findProb  (  n     x     y     k  ):   # Initialize memo to store results   memo   =   [[[  -  1   for   _   in   range  (  k   +   1  )]   for   _   in   range  (  n  )]   for   _   in   range  (  n  )]   return   knightProbability  (  n     x     y     k     memo  )   n     x     y     k   =   8     0     0     3   print  (  findProb  (  n     x     y     k  ))   
C#
   // C# program to find the probability of the   // knight to remain inside the chessboard   using     System  ;   class     GfG     {      // recursive function to calculate      // knight probability      static     double     KnightProbability  (  int     n       int     x           int     y       int     k       double  []     memo  )     {      // Base case initial probability      if     (  k     ==     0  )     return     1.0  ;      // check if already calculated      if     (  memo  [  x       y       k  ]     !=     -  1  )     return     memo  [  x       y       k  ];      int  []     directions     =     {{  1       2  }     {  2       1  }     {  2       -  1  }     {  1       -  2  }      {  -  1       -  2  }     {  -  2       -  1  }     {  -  2       1  }     {  -  1       2  }};      memo  [  x       y       k  ]     =     0  ;      double     cur     =     0.0  ;      // for every position reachable from (x y)      for     (  int     i     =     0  ;     i      <     8  ;     i  ++  )     {      int     u     =     x     +     directions  [  i       0  ];      int     v     =     y     +     directions  [  i       1  ];      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )     {      cur     +=     KnightProbability  (  n       u       v       k     -     1       memo  )     /     8.0  ;      }      }      return     memo  [  x       y       k  ]     =     cur  ;      }      // Function to find the probability      static     double     FindProb  (  int     n       int     x       int     y       int     k  )     {      // Initialize memo to store results      double  []     memo     =     new     double  [  n       n       k     +     1  ];      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  int     j     =     0  ;     j      <     n  ;     j  ++  )     {      for     (  int     m     =     0  ;     m      <=     k  ;     m  ++  )     {      memo  [  i       j       m  ]     =     -  1  ;      }      }      }      return     KnightProbability  (  n       x       y       k       memo  );      }      static     void     Main  ()     {      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      Console  .  WriteLine  (  FindProb  (  n       x       y       k  ));      }   }   
JavaScript
   // JavaScript program to find the probability of the   // knight to remain inside the chessboard   // recursive function to calculate   // knight probability   function     knightProbability  (  n       x       y       k       memo  )     {      // Base case initial probability      if     (  k     ===     0  )     return     1.0  ;      // check if already calculated      if     (  memo  [  x  ][  y  ][  k  ]     !==     -  1  )     return     memo  [  x  ][  y  ][  k  ];      const     directions     =     [      [  1       2  ]     [  2       1  ]     [  2       -  1  ]     [  1       -  2  ]      [  -  1       -  2  ]     [  -  2       -  1  ]     [  -  2       1  ]     [  -  1       2  ]      ];      memo  [  x  ][  y  ][  k  ]     =     0  ;      let     cur     =     0.0  ;      // for every position reachable from (x y)      for     (  let     d     of     directions  )     {      const     u     =     x     +     d  [  0  ];      const     v     =     y     +     d  [  1  ];      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )     {      cur     +=     knightProbability  (  n       u       v       k     -     1       memo  )     /     8.0  ;      }      }      return     memo  [  x  ][  y  ][  k  ]     =     cur  ;   }   // Function to find the probability   function     findProb  (  n       x       y       k  )     {      // Initialize memo to store results      const     memo     =     Array  .  from  ({     length  :     n     }     ()     =>      Array  .  from  ({     length  :     n     }     ()     =>     Array  (  k     +     1  ).  fill  (  -  1  )));      return     knightProbability  (  n       x       y       k       memo  ).  toFixed  (  6  );   }   const     n     =     8       x     =     0       y     =     0       k     =     3  ;      console  .  log  (  findProb  (  n       x       y       k  ));   

Izvade
0.125  

No apakšas uz augšu Dp (tabulācijas) izmantošana — O(n*n*k) laiks un O(n*n*k) telpa

Iepriekš minēto pieeju var optimizēt, izmantojot no apakšas uz augšu tabulēšana, samazinot papildu vietu, kas nepieciešama rekursīvai stekam. Ideja ir saglabāt 3 D masīvs dp[][][] kur dp[i][j][k] saglabā iespējamību, ka bruņinieks būs šūnā (i j) pēc k kustas. Inicializējiet 0 stāvoklis dp ar vērtību 1 . Katrai nākamajai kustībai varbūtība no bruņinieka būs vienāds uz vidēji no varbūtības iepriekšējā 8 pozīcijas pēc k-1 kustas.

C++
   // C++ program to find the probability of the   // knight to remain inside the chessboard   #include          using     namespace     std  ;   // Function to find the probability   double     findProb  (  int     n       int     x       int     y       int     k  )     {      // Initialize dp to store results of each step      vector   <  vector   <  vector   <  double  >>>     dp  (  n           vector   <  vector   <  double  >>  (  n        vector   <  double  >     (  k  +  1  )));          // Initialize dp for step 0      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      dp  [  i  ][  j  ][  0  ]     =     1.0  ;      }      }      vector   <  vector   <  int  >>     directions     =     {      {  1       2  }     {  2       1  }     {  2       -1  }     {  1       -2  }         {  -1       -2  }     {  -2       -1  }     {  -2       1  }     {  -1       2  }      };      for     (  int     move     =     1  ;     move      <=     k  ;     move  ++  )     {          // find probability for cell (i j)      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      double     cur     =     0.0  ;      // for every position reachable from (xy)      for     (  auto     d  :  directions  )     {      int     u     =     i     +     d  [  0  ];      int     v     =     j     +     d  [  1  ];      // if this position lie inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     dp  [  u  ][  v  ][  move     -     1  ]     /     8.0  ;      }      // store the result      dp  [  i  ][  j  ][  move  ]     =     cur  ;      }      }      }      // return the result      return     dp  [  x  ][  y  ][  k  ];   }   int     main  (){      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      cout      < <     findProb  (  n       x       y       k  )      < <     endl  ;      return     0  ;   }   
Java
   // Java program to find the probability of the   // knight to remain inside the chessboard   import     java.util.*  ;   class   GfG     {      // Function to find the probability      static     double     findProb  (  int     n       int     x       int     y       int     k  )     {      // Initialize dp to store results of each step      double  [][][]     dp     =     new     double  [  n  ][  n  ][  k     +     1  ]  ;      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  int     j     =     0  ;     j      <     n  ;     j  ++  )     {      dp  [  i  ][  j  ][  0  ]     =     1  ;      }      }      int  [][]     directions     =     {      {  1       2  }     {  2       1  }     {  2       -  1  }     {  1       -  2  }         {  -  1       -  2  }     {  -  2       -  1  }     {  -  2       1  }     {  -  1       2  }      };      for     (  int     move     =     1  ;     move      <=     k  ;     move  ++  )     {      // find probability for cell (i j)      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      double     cur     =     0.0  ;      // for every position reachable from (x y)      for     (  int  []     d     :     directions  )     {      int     u     =     i     +     d  [  0  ]  ;      int     v     =     j     +     d  [  1  ]  ;      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )     {      cur     +=     dp  [  u  ][  v  ][  move     -     1  ]     /     8.0  ;      }      }      // store the result      dp  [  i  ][  j  ][  move  ]     =     cur  ;      }      }      }      // return the result      return     dp  [  x  ][  y  ][  k  ]  ;      }      public     static     void     main  (  String  []     args  )     {      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      System  .  out  .  println  (  findProb  (  n       x       y       k  ));      }   }   
Python
   # Python program to find the probability of the   # knight to remain inside the chessboard   # Function to find the probability   def   findProb  (  n     x     y     k  ):   # Initialize dp to store results of each step   dp   =   [[[  0   for   _   in   range  (  k   +   1  )]   for   _   in   range  (  n  )]   for   _   in   range  (  n  )]   for   i   in   range  (  n  ):   for   j   in   range  (  n  ):   dp  [  i  ][  j  ][  0  ]   =   1.0   directions   =   [[  1     2  ]   [  2     1  ]   [  2     -  1  ]   [  1     -  2  ]   [  -  1     -  2  ]   [  -  2     -  1  ]   [  -  2     1  ]   [  -  1     2  ]]   for   move   in   range  (  1     k   +   1  ):   # find probability for cell (i j)   for   i   in   range  (  n  ):   for   j   in   range  (  n  ):   cur   =   0.0   # for every position reachable from (x y)   for   d   in   directions  :   u   =   i   +   d  [  0  ]   v   =   j   +   d  [  1  ]   # if this position lies inside the board   if   0    <=   u    <   n   and   0    <=   v    <   n  :   cur   +=   dp  [  u  ][  v  ][  move   -   1  ]   /   8.0   # store the result   dp  [  i  ][  j  ][  move  ]   =   cur   # return the result   return   dp  [  x  ][  y  ][  k  ]   if   __name__   ==   '__main__'  :   n     x     y     k   =   8     0     0     3   print  (  findProb  (  n     x     y     k  ))   
C#
   // C# program to find the probability of the   // knight to remain inside the chessboard   using     System  ;   class     GfG     {      // Function to find the probability      static     double     findProb  (  int     n       int     x       int     y       int     k  )     {      // Initialize dp to store results of each step      double  []     dp     =     new     double  [  n       n       k     +     1  ];      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  int     j     =     0  ;     j      <     n  ;     j  ++  )     {      dp  [  i       j       0  ]     =     1.0  ;      }      }      int  []     directions     =     {{  1       2  }     {  2       1  }     {  2       -  1  }     {  1       -  2  }         {  -  1       -  2  }     {  -  2       -  1  }     {  -  2       1  }     {  -  1       2  }};      for     (  int     move     =     1  ;     move      <=     k  ;     move  ++  )     {      // find probability for cell (i j)      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      double     cur     =     0.0  ;      // for every position reachable from (x y)      for     (  int     d     =     0  ;     d      <     directions  .  GetLength  (  0  );     d  ++  )     {      int     u     =     i     +     directions  [  d       0  ];      int     v     =     j     +     directions  [  d       1  ];      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )     {      cur     +=     dp  [  u       v       move     -     1  ]     /     8.0  ;      }      }      // store the result      dp  [  i       j       move  ]     =     cur  ;      }      }      }      // return the result      return     dp  [  x       y       k  ];      }      static     void     Main  (  string  []     args  )     {      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      Console  .  WriteLine  (  findProb  (  n       x       y       k  ));      }   }   
JavaScript
   // JavaScript program to find the probability of the   // knight to remain inside the chessboard   // Function to find the probability   function     findProb  (  n       x       y       k  )     {      // Initialize dp to store results of each step      let     dp     =     Array  .  from  ({     length  :     n     }     ()     =>         Array  .  from  ({     length  :     n     }     ()     =>     Array  (  k     +     1  ).  fill  (  0  ))      );      // Initialize dp for step 0      for     (  let     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  let     j     =     0  ;     j      <     n  ;     ++  j  )     {      dp  [  i  ][  j  ][  0  ]     =     1.0  ;      }      }          let     directions     =     [[  1       2  ]     [  2       1  ]     [  2       -  1  ]     [  1       -  2  ]         [  -  1       -  2  ]     [  -  2       -  1  ]     [  -  2       1  ]     [  -  1       2  ]];      for     (  let     move     =     1  ;     move      <=     k  ;     move  ++  )     {          // find probability for cell (i j)      for     (  let     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  let     j     =     0  ;     j      <     n  ;     j  ++  )     {      let     cur     =     0.0  ;      // for every position reachable from (x y)      for     (  let     d     of     directions  )     {      let     u     =     i     +     d  [  0  ];      let     v     =     j     +     d  [  1  ];      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )     {      cur     +=     dp  [  u  ][  v  ][  move     -     1  ]     /     8.0  ;      }      }      // store the result      dp  [  i  ][  j  ][  move  ]     =     cur  ;      }      }      }      // return the result      return     dp  [  x  ][  y  ][  k  ].  toFixed  (  6  );   }   let     n     =     8       x     =     0       y     =     0       k     =     3  ;   console  .  log  (  findProb  (  n       x       y       k  ));   

Izvade
0.125  

Izmantojot telpu Optimizēts Dp - O(n*n*k) laiks un O(n*n) telpa

Iepriekš minētā pieeja prasa tikai iepriekšējā varbūtību stāvoklis, lai aprēķinātu strāva norādiet šādi tikai uz iepriekšējā veikals ir jāuzglabā. Ideja ir izveidot divus 2D masīvi prevMove[][] un currMove[][] kur

  • prevMove[i][j] saglabā iespējamību, ka bruņinieks būs (i j) punktā līdz iepriekšējai kustībai. Sākotnējam stāvoklim tas tiek inicializēts ar vērtību 1.
  • currMove[i][j] saglabā pašreizējā stāvokļa varbūtību.

Darbojas līdzīgi iepriekš minētajai pieejai un plkst beigas katras iterācijas atjaunināt iepriekšējoPārvietot[][] ar saglabāto vērtību currMove[][].

C++
   // C++ program to find the probability of the   // knight to remain inside the chessboard   #include          using     namespace     std  ;   // Function to find the probability   double     findProb  (  int     n       int     x       int     y       int     k  )     {      // dp to store results of previous move      vector   <  vector   <  double  >>     prevMove  (  n       vector   <  double  >  (  n       1  ));      // dp to store results of current move      vector   <  vector   <  double  >>     currMove  (  n       vector   <  double  >  (  n       0  ));      vector   <  vector   <  int  >>     directions     =     {      {  1       2  }     {  2       1  }     {  2       -1  }     {  1       -2  }         {  -1       -2  }     {  -2       -1  }     {  -2       1  }     {  -1       2  }      };      for     (  int     move     =     1  ;     move      <=     k  ;     move  ++  )     {          // find probability for cell (i j)      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      double     cur     =     0.0  ;      // for every position reachable from (xy)      for     (  auto     d  :  directions  )     {      int     u     =     i     +     d  [  0  ];      int     v     =     j     +     d  [  1  ];      // if this position lie inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     prevMove  [  u  ][  v  ]     /     8.0  ;      }      // store the result      currMove  [  i  ][  j  ]     =     cur  ;      }      }      // update previous state      prevMove     =     currMove  ;      }      // return the result      return     prevMove  [  x  ][  y  ];   }   int     main  (){      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      cout      < <     findProb  (  n       x       y       k  )      < <     endl  ;      return     0  ;   }   
Java
   // Java program to find the probability of the   // knight to remain inside the chessboard   class   GfG     {      // Function to find the probability      static     double     findProb  (  int     n       int     x       int     y       int     k  )     {      // dp to store results of previous move      double  [][]     prevMove     =     new     double  [  n  ][  n  ]  ;      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  int     j     =     0  ;     j      <     n  ;     j  ++  )     {      prevMove  [  i  ][  j  ]     =     1.0  ;      }      }      // dp to store results of current move      double  [][]     currMove     =     new     double  [  n  ][  n  ]  ;      int  [][]     directions     =     {      {  1       2  }     {  2       1  }     {  2       -  1  }     {  1       -  2  }      {  -  1       -  2  }     {  -  2       -  1  }     {  -  2       1  }     {  -  1       2  }      };      for     (  int     move     =     1  ;     move      <=     k  ;     move  ++  )     {      // find probability for cell (i j)      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      double     cur     =     0.0  ;      // for every position reachable from (xy)      for     (  int  []     d     :     directions  )     {      int     u     =     i     +     d  [  0  ]  ;      int     v     =     j     +     d  [  1  ]  ;      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     prevMove  [  u  ][  v  ]     /     8.0  ;      }      // store the result      currMove  [  i  ][  j  ]     =     cur  ;      }      }      // update previous state      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )     {      System  .  arraycopy  (  currMove  [  i  ]       0       prevMove  [  i  ]       0       n  );      }      }      // return the result      return     prevMove  [  x  ][  y  ]  ;      }      public     static     void     main  (  String  []     args  )     {      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      System  .  out  .  println  (  findProb  (  n       x       y       k  ));      }   }   
Python
   # Python program to find the probability of the   # knight to remain inside the chessboard   def   findProb  (  n     x     y     k  ):   # dp to store results of previous move   prevMove   =   [[  1.0  ]   *   n   for   _   in   range  (  n  )]   # dp to store results of current move   currMove   =   [[  0.0  ]   *   n   for   _   in   range  (  n  )]   directions   =   [   [  1     2  ]   [  2     1  ]   [  2     -  1  ]   [  1     -  2  ]   [  -  1     -  2  ]   [  -  2     -  1  ]   [  -  2     1  ]   [  -  1     2  ]   ]   for   move   in   range  (  1     k   +   1  ):   # find probability for cell (i j)   for   i   in   range  (  n  ):   for   j   in   range  (  n  ):   cur   =   0.0   # for every position reachable from (xy)   for   d   in   directions  :   u     v   =   i   +   d  [  0  ]   j   +   d  [  1  ]   # if this position lies inside the board   if   0    <=   u    <   n   and   0    <=   v    <   n  :   cur   +=   prevMove  [  u  ][  v  ]   /   8.0   # store the result   currMove  [  i  ][  j  ]   =   cur   # update previous state   prevMove   =   [  row  [:]   for   row   in   currMove  ]   # return the result   return   prevMove  [  x  ][  y  ]   if   __name__   ==   '__main__'  :   n     x     y     k   =   8     0     0     3   print  (  findProb  (  n     x     y     k  ))   
C#
   // C# program to find the probability of the   // knight to remain inside the chessboard   using     System  ;   class     GfG     {      // Function to find the probability      static     double     findProb  (  int     n       int     x       int     y       int     k  )     {      // dp to store results of previous move      double  []     prevMove     =     new     double  [  n       n  ];      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )      for     (  int     j     =     0  ;     j      <     n  ;     j  ++  )      prevMove  [  i       j  ]     =     1.0  ;      // dp to store results of current move      double  []     currMove     =     new     double  [  n       n  ];      int  []     directions     =     {      {  1       2  }     {  2       1  }     {  2       -  1  }     {  1       -  2  }      {  -  1       -  2  }     {  -  2       -  1  }     {  -  2       1  }     {  -  1       2  }      };      for     (  int     move     =     1  ;     move      <=     k  ;     move  ++  )     {      // find probability for cell (i j)      for     (  int     i     =     0  ;     i      <     n  ;     ++  i  )     {      for     (  int     j     =     0  ;     j      <     n  ;     ++  j  )     {      double     cur     =     0.0  ;      // for every position reachable from (xy)      for     (  int     d     =     0  ;     d      <     directions  .  GetLength  (  0  );     d  ++  )     {      int     u     =     i     +     directions  [  d       0  ];      int     v     =     j     +     directions  [  d       1  ];      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     prevMove  [  u       v  ]     /     8.0  ;      }      // store the result      currMove  [  i       j  ]     =     cur  ;      }      }      // update previous state      Array  .  Copy  (  currMove       prevMove       n     *     n  );      }      // return the result      return     prevMove  [  x       y  ];      }      static     void     Main  ()     {      int     n     =     8       x     =     0       y     =     0       k     =     3  ;      Console  .  WriteLine  (  findProb  (  n       x       y       k  ));      }   }   
JavaScript
   // JavaScript program to find the probability of the   // knight to remain inside the chessboard   function     findProb  (  n       x       y       k  )     {      // dp to store results of previous move      let     prevMove     =     Array  .  from  ({     length  :     n     }         ()     =>     Array  (  n  ).  fill  (  1.0  ));      // dp to store results of current move      let     currMove     =     Array  .  from  ({     length  :     n     }         ()     =>     Array  (  n  ).  fill  (  0.0  ));      const     directions     =     [      [  1       2  ]     [  2       1  ]     [  2       -  1  ]     [  1       -  2  ]      [  -  1       -  2  ]     [  -  2       -  1  ]     [  -  2       1  ]     [  -  1       2  ]      ];      for     (  let     move     =     1  ;     move      <=     k  ;     move  ++  )     {      // find probability for cell (i j)      for     (  let     i     =     0  ;     i      <     n  ;     i  ++  )     {      for     (  let     j     =     0  ;     j      <     n  ;     j  ++  )     {      let     cur     =     0.0  ;      // for every position reachable from (xy)      for     (  let     d     of     directions  )     {      let     u     =     i     +     d  [  0  ];      let     v     =     j     +     d  [  1  ];      // if this position lies inside the board      if     (  u     >=     0     &&     u      <     n     &&     v     >=     0     &&     v      <     n  )      cur     +=     prevMove  [  u  ][  v  ]     /     8.0  ;      }      // store the result      currMove  [  i  ][  j  ]     =     cur  ;      }      }      // update previous state      prevMove     =     currMove  .  map  (  row     =>     [...  row  ]);      }      // return the result      return     prevMove  [  x  ][  y  ].  toFixed  (  6  );   }   let     n     =     8       x     =     0       y     =     0       k     =     3  ;   console  .  log  (  findProb  (  n       x       y       k  ));   

Izvade
0.125  
Izveidojiet viktorīnu