static void printGroups ( int n ) {
  int x = 1 ;
  int y = n * n ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) {
    for ( int j = 1 ;
    j <= n / 2 ;
    j ++ ) {
      System . out . print ( "{ " + x + ", " + y + "} " ) ;
      x ++ ;
      y -- ;
    }
    System . out . println ( ) ;
  }
}

static void printGroups ( int n ) { int x = 1 ; int y = n * n ; for ( int i = 1 ; i <= n ; i ++ ) { for ( int j = 1 ; j <= n / 2 ; j ++ ) { System . out . print ( " { ▁ " + x + " , ▁ " + y + " } ▁ " ) ; x ++ ; y -- ; } System . out . println ( ) ; } }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (integral_type) name: (identifier))) body: (block (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (identifier)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))) update: (update_expression (identifier)) body: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (binary_expression left: (binary_expression left: (binary_expression left: (string_literal) right: (identifier)) right: (string_literal)) right: (identifier)) right: (string_literal))))) (expression_statement (update_expression (identifier))) (expression_statement (update_expression (identifier))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list)))))))