// C++ program to find how many mirror can transfer   // light from bottom to right   #include          using     namespace     std  ;   // method returns number of mirror which can transfer   // light from bottom to right   int     maximumMirrorInMatrix  (  string     mat  []     int     N  )   {      // To store first obstacles horizontally (from right)      // and vertically (from bottom)      int     horizontal  [  N  ]     vertical  [  N  ];      // initialize both array as -1 signifying no obstacle      memset  (  horizontal       -1       sizeof  (  horizontal  ));      memset  (  vertical       -1       sizeof  (  vertical  ));      // looping matrix to mark column for obstacles      for     (  int     i  =  0  ;     i   <  N  ;     i  ++  )      {      for     (  int     j  =  N  -1  ;     j  >=  0  ;     j  --  )      {      if     (  mat  [  i  ][  j  ]     ==     'B'  )      continue  ;      // mark rightmost column with obstacle      horizontal  [  i  ]     =     j  ;      break  ;      }      }      // looping matrix to mark rows for obstacles      for     (  int     j  =  0  ;     j   <  N  ;     j  ++  )      {      for     (  int     i  =  N  -1  ;     i  >=  0  ;     i  --  )      {      if     (  mat  [  i  ][  j  ]     ==     'B'  )      continue  ;      // mark leftmost row with obstacle      vertical  [  j  ]     =     i  ;      break  ;      }      }      int     res     =     0  ;     // Initialize result      // if there is not obstacle on right or below      // then mirror can be placed to transfer light      for     (  int     i     =     0  ;     i      <     N  ;     i  ++  )      {      for     (  int     j     =     0  ;     j      <     N  ;     j  ++  )      {      /* if i > vertical[j] then light can from bottom    if j > horizontal[i] then light can go to right */      if     (  i     >     vertical  [  j  ]     &&     j     >     horizontal  [  i  ])      {      /* uncomment this code to print actual mirror    position also    cout  < < i  < < ' '  < < j  < < endl; */      res  ++  ;      }      }      }      return     res  ;   }   // Driver code to test above method   int     main  ()   {      int     N     =     5  ;      // B - Blank O - Obstacle      string     mat  [  N  ]     =     {  'BBOBB'        'BBBBO'        'BBBBB'        'BOOBO'        'BBBOB'      };      cout      < <     maximumMirrorInMatrix  (  mat       N  )      < <     endl  ;      return     0  ;   }   

   // Java program to find how many mirror can transfer   // light from bottom to right   import     java.util.*  ;   class   GFG      {      // method returns number of mirror which can transfer      // light from bottom to right      static     int     maximumMirrorInMatrix  (  String     mat  []       int     N  )         {      // To store first obstacles horizontally (from right)      // and vertically (from bottom)      int  []     horizontal     =     new     int  [  N  ]  ;      int  []     vertical     =     new     int  [  N  ]  ;      // initialize both array as -1 signifying no obstacle      Arrays  .  fill  (  horizontal       -  1  );      Arrays  .  fill  (  vertical       -  1  );          // looping matrix to mark column for obstacles      for     (  int     i     =     0  ;     i      <     N  ;     i  ++  )         {      for     (  int     j     =     N     -     1  ;     j     >=     0  ;     j  --  )         {      if     (  mat  [  i  ]  .  charAt  (  j  )     ==     'B'  )      {      continue  ;      }      // mark rightmost column with obstacle      horizontal  [  i  ]     =     j  ;      break  ;      }      }      // looping matrix to mark rows for obstacles      for     (  int     j     =     0  ;     j      <     N  ;     j  ++  )         {      for     (  int     i     =     N     -     1  ;     i     >=     0  ;     i  --  )         {      if     (  mat  [  i  ]  .  charAt  (  j  )     ==     'B'  )         {      continue  ;      }      // mark leftmost row with obstacle      vertical  [  j  ]     =     i  ;      break  ;      }      }      int     res     =     0  ;     // Initialize result      // if there is not obstacle on right or below      // then mirror can be placed to transfer light      for     (  int     i     =     0  ;     i      <     N  ;     i  ++  )      {      for     (  int     j     =     0  ;     j      <     N  ;     j  ++  )         {      /* if i > vertical[j] then light can from bottom    if j > horizontal[i] then light can go to right */      if     (  i     >     vertical  [  j  ]     &&     j     >     horizontal  [  i  ]  )      {      /* uncomment this code to print actual mirror    position also    cout  < < i  < < ' '  < < j  < < endl; */      res  ++  ;      }      }      }      return     res  ;      }   // Driver code   public     static     void     main  (  String  []     args  )      {      int     N     =     5  ;      // B - Blank O - Obstacle      String     mat  []     =     {  'BBOBB'        'BBBBO'        'BBBBB'        'BOOBO'        'BBBOB'      };      System  .  out  .  println  (  maximumMirrorInMatrix  (  mat       N  ));   }   }   /* This code is contributed by PrinciRaj1992 */   

   # Python3 program to find how many mirror can transfer   # light from bottom to right   # method returns number of mirror which can transfer   # light from bottom to right   def   maximumMirrorInMatrix  (  mat     N  ):   # To store first obstacles horizontally (from right)   # and vertically (from bottom)   horizontal   =   [  -  1   for   i   in   range  (  N  )]   vertical   =   [  -  1   for   i   in   range  (  N  )];   # looping matrix to mark column for obstacles   for   i   in   range  (  N  ):   for   j   in   range  (  N   -   1     -  1     -  1  ):   if   (  mat  [  i  ][  j  ]   ==   'B'  ):   continue  ;   # mark rightmost column with obstacle   horizontal  [  i  ]   =   j  ;   break  ;   # looping matrix to mark rows for obstacles   for   j   in   range  (  N  ):   for   i   in   range  (  N   -   1     -  1     -  1  ):   if   (  mat  [  i  ][  j  ]   ==   'B'  ):   continue  ;   # mark leftmost row with obstacle   vertical  [  j  ]   =   i  ;   break  ;   res   =   0  ;   # Initialize result   # if there is not obstacle on right or below   # then mirror can be placed to transfer light   for   i   in   range  (  N  ):   for   j   in   range  (  N  ):          ''' if i > vertical[j] then light can from bottom    if j > horizontal[i] then light can go to right '''   if   (  i   >   vertical  [  j  ]   and   j   >   horizontal  [  i  ]):          ''' uncomment this code to print actual mirror    position also'''   res  +=  1  ;   return   res  ;   # Driver code to test above method   N   =   5  ;   # B - Blank O - Obstacle   mat   =   [  'BBOBB'     'BBBBO'     'BBBBB'     'BOOBO'     'BBBOB'   ];   print  (  maximumMirrorInMatrix  (  mat     N  ));   # This code is contributed by rutvik_56.   

   // C# program to find how many mirror can transfer   // light from bottom to right   using     System  ;       class     GFG      {      // method returns number of mirror which can transfer      // light from bottom to right      static     int     maximumMirrorInMatrix  (  String     []  mat       int     N  )         {      // To store first obstacles horizontally (from right)      // and vertically (from bottom)      int  []     horizontal     =     new     int  [  N  ];      int  []     vertical     =     new     int  [  N  ];      // initialize both array as -1 signifying no obstacle      for     (  int     i     =     0  ;     i      <     N  ;     i  ++  )         {      horizontal  [  i  ]  =-  1  ;      vertical  [  i  ]  =-  1  ;      }          // looping matrix to mark column for obstacles      for     (  int     i     =     0  ;     i      <     N  ;     i  ++  )         {      for     (  int     j     =     N     -     1  ;     j     >=     0  ;     j  --  )         {      if     (  mat  [  i  ][  j  ]     ==     'B'  )      {      continue  ;      }      // mark rightmost column with obstacle      horizontal  [  i  ]     =     j  ;      break  ;      }      }      // looping matrix to mark rows for obstacles      for     (  int     j     =     0  ;     j      <     N  ;     j  ++  )         {      for     (  int     i     =     N     -     1  ;     i     >=     0  ;     i  --  )         {      if     (  mat  [  i  ][  j  ]     ==     'B'  )         {      continue  ;      }      // mark leftmost row with obstacle      vertical  [  j  ]     =     i  ;      break  ;      }      }      int     res     =     0  ;     // Initialize result      // if there is not obstacle on right or below      // then mirror can be placed to transfer light      for     (  int     i     =     0  ;     i      <     N  ;     i  ++  )      {      for     (  int     j     =     0  ;     j      <     N  ;     j  ++  )         {      /* if i > vertical[j] then light can from bottom    if j > horizontal[i] then light can go to right */      if     (  i     >     vertical  [  j  ]     &&     j     >     horizontal  [  i  ])      {      /* uncomment this code to print actual mirror    position also    cout  < < i  < < ' '  < < j  < < endl; */      res  ++  ;      }      }      }      return     res  ;      }   // Driver code   public     static     void     Main  (  String  []     args  )      {      int     N     =     5  ;      // B - Blank O - Obstacle      String     []  mat     =     {  'BBOBB'        'BBBBO'        'BBBBB'        'BOOBO'        'BBBOB'      };      Console  .  WriteLine  (  maximumMirrorInMatrix  (  mat       N  ));   }   }   // This code is contributed by Princi Singh   

    <  script  >   // JavaScript program to find how many mirror can transfer   // light from bottom to right   // method returns number of mirror which can transfer   // light from bottom to right   function     maximumMirrorInMatrix  (  mat       N  )      {      // To store first obstacles horizontally (from right)      // and vertically (from bottom)      var     horizontal     =     Array  (  N  ).  fill  (  -  1  );      var     vertical     =     Array  (  N  ).  fill  (  -  1  );          // looping matrix to mark column for obstacles      for     (  var     i     =     0  ;     i      <     N  ;     i  ++  )         {      for     (  var     j     =     N     -     1  ;     j     >=     0  ;     j  --  )         {      if     (  mat  [  i  ][  j  ]     ==     'B'  )      {      continue  ;      }      // mark rightmost column with obstacle      horizontal  [  i  ]     =     j  ;      break  ;      }      }      // looping matrix to mark rows for obstacles      for     (  var     j     =     0  ;     j      <     N  ;     j  ++  )         {      for     (  var     i     =     N     -     1  ;     i     >=     0  ;     i  --  )         {      if     (  mat  [  i  ][  j  ]     ==     'B'  )         {      continue  ;      }      // mark leftmost row with obstacle      vertical  [  j  ]     =     i  ;      break  ;      }      }      var     res     =     0  ;     // Initialize result      // if there is not obstacle on right or below      // then mirror can be placed to transfer light      for     (  var     i     =     0  ;     i      <     N  ;     i  ++  )      {      for     (  var     j     =     0  ;     j      <     N  ;     j  ++  )         {      /* if i > vertical[j] then light can from bottom    if j > horizontal[i] then light can go to right */      if     (  i     >     vertical  [  j  ]     &&     j     >     horizontal  [  i  ])      {      /* uncomment this code to print actual mirror    position also    cout  < < i  < < ' '  < < j  < < endl; */      res  ++  ;      }      }      }      return     res  ;   }   // Driver code   var     N     =     5  ;   // B - Blank O - Obstacle   var     mat     =     [  'BBOBB'        'BBBBO'        'BBBBB'        'BOOBO'        'BBBOB'   ];   document  .  write  (  maximumMirrorInMatrix  (  mat       N  ));    <  /script>