static String commonPrefix ( String arr [ ] , int n ) {
  root = new TrieNode ( ) ;
  constructTrie ( arr , n ) ;
  return walkTrie ( ) ;
}

static String commonPrefix ( String arr [ ] , int n ) { root = new TrieNode ( ) ; constructTrie ( arr , n ) ; return walkTrie ( ) ; }
(method_declaration (modifiers) type: (type_identifier) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier) dimensions: (dimensions)) (formal_parameter type: (integral_type) name: (identifier))) body: (block (expression_statement (assignment_expression left: (identifier) right: (object_creation_expression type: (type_identifier) arguments: (argument_list)))) (expression_statement (method_invocation name: (identifier) arguments: (argument_list (identifier) (identifier)))) (return_statement (method_invocation name: (identifier) arguments: (argument_list)))))