Smjer na zadnjem kvadratnom bloku

S obzirom na R x C (1 <= R C <= 1000000000) grid and initial position as top left corner and direction as east. Now we start running in forward direction and cross each square blocks of matrix. Whenever we find dead end or reach a cell that is already visited we take right because we can not cross the visited square blocks again. Tell the direction when we will be at last square block.

Na primjer: Razmotrimo slučaj s R = 3 C = 3. Put koji slijedi bit će (0 0) -- (0 1) -- (0 2) -- (1 2) -- (2 2) -- (2 1) -- (2 0) -- (1 0) -- (1 1). U ovom trenutku svi su kvadrati posjećeni i okrenuti su desno. 

Primjeri:  

Input : R = 1 C = 1 Output : Right Input : R = 2 C = 2 Output : Left Input : R = 3 C = 1 Output : Down Input : R = 3 C = 3 Output : Right 

Jednostavno rješenje: Jedno jednostavno rješenje za ovaj problem je napraviti R x C matricu inicijaliziranu s nulom i preći je u spiralnom obliku i uzeti varijablu 'Dir' koja govori trenutni smjer. Kad god smo na kraju bilo kojeg retka ili stupca, skrenite desno i promijenite vrijednost 'Dir' prema vašem trenutnom smjeru. Sada slijedite zadane uvjete: 

  • Ako prelazite gornji red, vaš trenutni smjer je desno.
  • Ako ste u desnom stupcu, vaš trenutni smjer je dolje.
  • Ako prelazite donji red, tada je vaš trenutni smjer lijevo.
  • Ako prelazite po lijevom stupcu, vaš trenutni smjer je gore.

Kada dođemo do posljednjeg kvadrata samo ispišite trenutni smjer tj.; vrijednost varijable 'Dir'. 
Vremenska i prostorna složenost za ovaj problem je O(R x C) i ovo će raditi samo za male vrijednosti R C, ali ovdje su R i C preveliki tako da stvaranje R x C matrice nije moguće za prevelike vrijednosti R i C.

Učinkovit pristup: Ovaj pristup zahtijeva malo promatranja i malo rada s papirom. Ovdje moramo razmotriti sve moguće slučajeve za R i C, a zatim samo trebamo staviti IF uvjet za sve moguće slučajeve. Evo nas sa svim mogućim uvjetima: 

  1. R != C i R je paran, a C neparan i R
  2. R != C i R je neparan, a C paran i R
  3. R != C i R je paran i C je paran i R
  4. R != C i R je neparan i C je neparan i R
  5. R != C i R je paran, a C neparan i R>C smjer će biti prema dolje.
  6. R != C i R je neparan, a C paran i R>C smjer će biti gore.
  7. R != C i R je paran i C je paran i R>C smjer će biti gore.
  8. R != C i R je neparan i C je neparan i R>C smjer će biti dolje.
  9. R == C i R je paran, a C je paran smjer će biti lijevo.
  10. R == C i R je neparan i C je neparan smjer će biti desno.

Ispod je implementacija gornje ideje. 

C++
   // C++ program to tell the Current direction in   // R x C grid   #include          using     namespace     std  ;   typedef     long     long     int     ll  ;   // Function which tells the Current direction   void     direction  (  ll     R       ll     C  )   {      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     !=     0     &&     R      <     C  )     {      cout      < <     'Left'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     ==     0     &&     R     >     C  )     {      cout      < <     'Up'      < <     endl  ;      return  ;      }      if     (  R     ==     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0  )     {      cout      < <     'Right'      < <     endl  ;      return  ;      }      if     (  R     ==     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0  )     {      cout      < <     'Left'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0     &&     R      <     C  )     {      cout      < <     'Right'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0     &&     R     >     C  )     {      cout      < <     'Down'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0     &&     R      <     C  )     {      cout      < <     'Left'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0     &&     R     >     C  )     {      cout      < <     'Up'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     !=     0     &&     R     >     C  )     {      cout      < <     'Down'      < <     endl  ;      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     ==     0     &&     R      <     C  )     {      cout      < <     'Right'      < <     endl  ;      return  ;      }   }   // Driver program to test the Cases   int     main  ()   {      ll     R     =     3       C     =     1  ;      direction  (  R       C  );      return     0  ;   }   
C
   // C program to tell the Current direction in   // R x C grid   #include         typedef     long     long     int     ll  ;   // Function which tells the Current direction   void     direction  (  ll     R       ll     C  )   {      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     !=     0     &&     R      <     C  )     {      printf  (  'Left  n  '  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     ==     0     &&     R     >     C  )     {      printf  (  'Up  n  '  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0  )     {      printf  (  'Right  n  '  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0  )     {      printf  (  'Left  n  '  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0     &&     R      <     C  )     {      printf  (  'Right  n  '  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0     &&     R     >     C  )     {      printf  (  'Down  n  '  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0     &&     R      <     C  )     {      printf  (  'Left  n  '  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0     &&     R     >     C  )     {      printf  (  'Up  n  '  );;      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     !=     0     &&     R     >     C  )     {      printf  (  'Down  n  '  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     ==     0     &&     R      <     C  )     {      printf  (  'Right  n  '  );      return  ;      }   }   // Driver program to test the Cases   int     main  ()   {      ll     R     =     3       C     =     1  ;      direction  (  R       C  );      return     0  ;   }   // This code is contributed by kothavvsaakash.   
Java
   // Java program to tell the Current direction in   // R x C grid   import     java.io.*  ;   class   GFG     {      // Function which tells the Current direction       static     void     direction  (  int     R       int     C  )      {      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     !=     0     &&     R      <     C  )     {      System  .  out  .  println  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     ==     0     &&     R     >     C  )     {      System  .  out  .  println  (  'Up'  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0  )     {      System  .  out  .  println  (  'Right'  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0  )     {      System  .  out  .  println  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0     &&     R      <     C  )     {      System  .  out  .  println  (  'Right'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     !=     0     &&     R     >     C  )     {      System  .  out  .  println  (  'Down'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0     &&     R      <     C  )     {      System  .  out  .  println  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     ==     0     &&     R     >     C  )     {      System  .  out  .  println  (  'Up'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&     C     %     2     !=     0     &&     R     >     C  )     {      System  .  out  .  println  (  'Down'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&     C     %     2     ==     0     &&     R      <     C  )     {      System  .  out  .  println  (  'Right'  );      return  ;      }      }      // Driver code      public     static     void     main  (  String  []     args  )      {      int     R     =     3       C     =     1  ;          direction  (  R       C  );      }   }   // This code is contributed by KRV.   
Python3
   # Python3 program to tell the Current    # direction in R x C grid   # Function which tells the Current direction   def   direction  (  R     C  ):   if   (  R   !=   C   and   R   %   2   ==   0   and   C   %   2   !=   0   and   R    <   C  ):   print  (  'Left'  )   return   if   (  R   !=   C   and   R   %   2   ==   0   and   C   %   2   ==   0   and   R   >   C  ):   print  (  'Up'  )   return   if   R   ==   C   and   R   %   2   !=   0   and   C   %   2   !=   0  :   print  (  'Right'  )   return   if   R   ==   C   and   R   %   2   ==   0   and   C   %   2   ==   0  :   print  (  'Left'  )   return   if   (  R   !=   C   and   R   %   2   !=   0   and   C   %   2   !=   0   and   R    <   C  ):   print  (  'Right'  )   return   if   (  R   !=   C   and   R   %   2   !=   0   and   C   %   2   !=   0   and   R   >   C  ):   print  (  'Down'  )   return   if   (  R   !=   C   and   R   %   2   ==   0   and   C   %   2   !=   0   and   R    <   C  ):   print  (  'Left'  )   return   if   (  R   !=   C   and   R   %   2   ==   0   and   C   %   2   ==   0   and   R   >   C  ):   print  (  'Up'  )   return   if   (  R   !=   C   and   R   %   2   !=   0   and   C   %   2   !=   0   and   R   >   C  ):   print  (  'Down'  )   return   if   (  R   !=   C   and   R   %   2   !=   0   and   C   %   2   !=   0   and   R    <   C  ):   print  (  'Right'  )   return   # Driver code   R   =   3  ;   C   =   1   direction  (  R     C  )   # This code is contributed by Shrikant13   
C#
   // C# program to tell the Current   // direction in R x C grid   using     System  ;   class     GFG   {          // Function which tells       // the Current direction       static     void     direction  (  int     R       int     C  )      {      if     (  R     !=     C     &&     R     %     2     ==     0     &&         C     %     2     !=     0     &&     R      <     C  )         {      Console  .  WriteLine  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&         C     %     2     ==     0     &&     R     >     C  )         {      Console  .  WriteLine  (  'Up'  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     !=     0     &&         C     %     2     !=     0  )         {      Console  .  WriteLine  (  'Right'  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     ==     0     &&         C     %     2     ==     0  )         {      Console  .  WriteLine  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&      C     %     2     !=     0     &&     R      <     C  )         {      Console  .  WriteLine  (  'Right'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&         C     %     2     !=     0     &&     R     >     C  )         {      Console  .  WriteLine  (  'Down'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&         C     %     2     ==     0     &&     R      <     C  )         {      Console  .  WriteLine  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&      C     %     2     ==     0     &&     R     >     C  )         {      Console  .  WriteLine  (  'Up'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&         C     %     2     !=     0     &&     R     >     C  )         {      Console  .  WriteLine  (  'Down'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&         C     %     2     ==     0     &&     R      <     C  )         {      Console  .  WriteLine  (  'Right'  );      return  ;      }      }      // Driver code      static     public     void     Main     ()      {      int     R     =     3       C     =     1  ;          direction  (  R       C  );      }   }   // This code is contributed by m_kit   
PHP
      // PHP program to tell the Current    // direction in R x C grid   // Function which tells   // the Current direction   function   direction  (  $R     $C  )   {   if   (  $R   !=   $C   &&   $R   %   2   ==   0   &&   $C   %   2   !=   0   &&   $R    <   $C  )   {   echo   'Left'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   !=   0   &&   $C   %   2   ==   0   &&   $R   >   $C  )   {   echo   'Up'     '  n  '  ;   return  ;   }   if   (  $R   ==   $C   &&   $R   %   2   !=   0   &&   $C   %   2   !=   0  )   {   echo   'Right'     '  n  '  ;   return  ;   }   if   (  $R   ==   $C   &&   $R   %   2   ==   0   &&   $C   %   2   ==   0  )   {   echo   'Left'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   !=   0   &&   $C   %   2   !=   0   &&   $R    <   $C  )   {   echo   'Right'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   !=   0   &&   $C   %   2   !=   0   &&   $R   >   $C  )   {   echo   'Down'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   ==   0   &&   $C   %   2   ==   0   &&   $R    <   $C  )   {   echo   'Left'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   ==   0   &&   $C   %   2   ==   0   &&   $R   >   $C  )   {   echo   'Up'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   ==   0   &&   $C   %   2   !=   0   &&   $R   >   $C  )   {   echo   'Down'     '  n  '  ;   return  ;   }   if   (  $R   !=   $C   &&   $R   %   2   !=   0   &&   $C   %   2   ==   0   &&   $R    <   $C  )   {   echo   'Right'     '  n  '  ;   return  ;   }   }   // Driver Code   $R   =   3  ;   $C   =   1  ;   direction  (  $R     $C  );   // This code is contributed by aj_36   ?>   
JavaScript
    <  script  >      // Javascript program to tell the Current      // direction in R x C grid          // Function which tells       // the Current direction       function     direction  (  R       C  )      {      if     (  R     !=     C     &&     R     %     2     ==     0     &&         C     %     2     !=     0     &&     R      <     C  )         {      document  .  write  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&         C     %     2     ==     0     &&     R     >     C  )         {      document  .  write  (  'Up'  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     !=     0     &&         C     %     2     !=     0  )         {      document  .  write  (  'Right'  );      return  ;      }      if     (  R     ==     C     &&     R     %     2     ==     0     &&         C     %     2     ==     0  )         {      document  .  write  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&         C     %     2     !=     0     &&     R      <     C  )         {      document  .  write  (  'Right'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&      C     %     2     !=     0     &&     R     >     C  )         {      document  .  write  (  'Down'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&      C     %     2     ==     0     &&     R      <     C  )         {      document  .  write  (  'Left'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&         C     %     2     ==     0     &&     R     >     C  )         {      document  .  write  (  'Up'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     ==     0     &&         C     %     2     !=     0     &&     R     >     C  )         {      document  .  write  (  'Down'  );      return  ;      }      if     (  R     !=     C     &&     R     %     2     !=     0     &&         C     %     2     ==     0     &&     R      <     C  )         {      document  .  write  (  'Right'  );      return  ;      }      }          let     R     =     3       C     =     1  ;          direction  (  R       C  );        <  /script>   

Izlaz
Down 

Vremenska složenost: O(1) 
Pomoćni prostor: O(1)

Ovaj je članak pregledao tim GeeksforGeeks.