// C++ program to print all permutations using   // Heap's algorithm   #include          using     namespace     std  ;   // Prints the array   void     printArr  (  int     a  []     int     n  )   {      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )      cout      < <     a  [  i  ]      < <     ' '  ;      printf  (  '  n  '  );   }   // Generating permutation using Heap Algorithm   void     heapPermutation  (  int     a  []     int     size       int     n  )   {      // if size becomes 1 then prints the obtained      // permutation      if     (  size     ==     1  )     {      printArr  (  a       n  );      return  ;      }      for     (  int     i     =     0  ;     i      <     size  ;     i  ++  )     {      heapPermutation  (  a       size     -     1       n  );      // if size is odd swap 0th i.e (first) and       // (size-1)th i.e (last) element      if     (  size     %     2     ==     1  )      swap  (  a  [  0  ]     a  [  size     -     1  ]);      // If size is even swap ith and       // (size-1)th i.e (last) element      else      swap  (  a  [  i  ]     a  [  size     -     1  ]);      }   }   // Driver code   int     main  ()   {      int     a  []     =     {     1       2       3     };      int     n     =     sizeof     a     /     sizeof     a  [  0  ];      heapPermutation  (  a       n       n  );      return     0  ;   }   

   // Java program to print all permutations using   // Heap's algorithm   import     java.io.*  ;   class   HeapAlgo     {      // Prints the array      void     printArr  (  int     a  []       int     n  )      {      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )      System  .  out  .  print  (  a  [  i  ]     +     ' '  );      System  .  out  .  println  ();      }      // Generating permutation using Heap Algorithm      void     heapPermutation  (  int     a  []       int     size       int     n  )      {      // if size becomes 1 then prints the obtained      // permutation      if     (  size     ==     1  )      printArr  (  a       n  );      for     (  int     i     =     0  ;     i      <     size  ;     i  ++  )     {      heapPermutation  (  a       size     -     1       n  );      // if size is odd swap 0th i.e (first) and      // (size-1)th i.e (last) element      if     (  size     %     2     ==     1  )     {      int     temp     =     a  [  0  ]  ;      a  [  0  ]     =     a  [  size     -     1  ]  ;      a  [  size     -     1  ]     =     temp  ;      }      // If size is even swap ith       // and (size-1)th i.e last element      else     {      int     temp     =     a  [  i  ]  ;      a  [  i  ]     =     a  [  size     -     1  ]  ;      a  [  size     -     1  ]     =     temp  ;      }      }      }      // Driver code      public     static     void     main  (  String     args  []  )      {      HeapAlgo     obj     =     new     HeapAlgo  ();      int     a  []     =     {     1       2       3     };      obj  .  heapPermutation  (  a       a  .  length       a  .  length  );      }   }   // This code has been contributed by Amit Khandelwal.   

   # Python program to print all permutations using   # Heap's algorithm   # Generating permutation using Heap Algorithm   def   heapPermutation  (  a     size  ):   # if size becomes 1 then prints the obtained   # permutation   if   size   ==   1  :   print  (  a  )   return   for   i   in   range  (  size  ):   heapPermutation  (  a     size  -  1  )   # if size is odd swap 0th i.e (first)   # and (size-1)th i.e (last) element   # else If size is even swap ith   # and (size-1)th i.e (last) element   if   size   &   1  :   a  [  0  ]   a  [  size  -  1  ]   =   a  [  size  -  1  ]   a  [  0  ]   else  :   a  [  i  ]   a  [  size  -  1  ]   =   a  [  size  -  1  ]   a  [  i  ]   # Driver code   a   =   [  1     2     3  ]   n   =   len  (  a  )   heapPermutation  (  a     n  )   # This code is contributed by ankush_953   # This code was cleaned up to by more pythonic by glubs9   

   // C# program to print all permutations using   // Heap's algorithm   using     System  ;   public     class     GFG     {      // Prints the array      static     void     printArr  (  int  []     a       int     n  )      {      for     (  int     i     =     0  ;     i      <     n  ;     i  ++  )      Console  .  Write  (  a  [  i  ]     +     ' '  );      Console  .  WriteLine  ();      }      // Generating permutation using Heap Algorithm      static     void     heapPermutation  (  int  []     a       int     size       int     n  )      {      // if size becomes 1 then prints the obtained      // permutation      if     (  size     ==     1  )      printArr  (  a       n  );      for     (  int     i     =     0  ;     i      <     size  ;     i  ++  )     {      heapPermutation  (  a       size     -     1       n  );      // if size is odd swap 0th i.e (first) and      // (size-1)th i.e (last) element      if     (  size     %     2     ==     1  )     {      int     temp     =     a  [  0  ];      a  [  0  ]     =     a  [  size     -     1  ];      a  [  size     -     1  ]     =     temp  ;      }      // If size is even swap ith and      // (size-1)th i.e (last) element      else     {      int     temp     =     a  [  i  ];      a  [  i  ]     =     a  [  size     -     1  ];      a  [  size     -     1  ]     =     temp  ;      }      }      }      // Driver code      public     static     void     Main  ()      {      int  []     a     =     {     1       2       3     };      heapPermutation  (  a       a  .  Length       a  .  Length  );      }   }   /* This Java code is contributed by 29AjayKumar*/   

    <  script  >   // JavaScript program to print all permutations using   // Heap's algorithm   // Prints the array   function     printArr  (  a    n  )   {      document  .  write  (  a  .  join  (  ' '  )  +  '  
'  );       }   // Generating permutation using Heap Algorithm   function     heapPermutation  (  a    size    n  )   {      // if size becomes 1 then prints the obtained      // permutation      if     (  size     ==     1  )      printArr  (  a       n  );          for     (  let     i     =     0  ;     i      <     size  ;     i  ++  )     {      heapPermutation  (  a       size     -     1       n  );          // if size is odd swap 0th i.e (first) and      // (size-1)th i.e (last) element      if     (  size     %     2     ==     1  )     {      let     temp     =     a  [  0  ];      a  [  0  ]     =     a  [  size     -     1  ];      a  [  size     -     1  ]     =     temp  ;      }          // If size is even swap ith      // and (size-1)th i.e last element      else     {      let     temp     =     a  [  i  ];      a  [  i  ]     =     a  [  size     -     1  ];      a  [  size     -     1  ]     =     temp  ;      }      }   }   // Driver code   let     a  =  [  1       2       3  ];   heapPermutation  (  a       a  .  length       a  .  length  );   // This code is contributed by rag2127    <  /script>