static String commonPrefixUtil ( String str1 , String str2 ) {
  String result = "" ;
  int n1 = str1 . length ( ) , n2 = str2 . length ( ) ;
  for ( int i = 0 , j = 0 ;
  i <= n1 - 1 && j <= n2 - 1 ;
  i ++ , j ++ ) {
    if ( str1 . charAt ( i ) != str2 . charAt ( j ) ) {
      break ;
    }
    result += str1 . charAt ( i ) ;
  }
  return ( result ) ;
}

static String commonPrefixUtil ( String str1 , String str2 ) { String result = " " ; int n1 = str1 . length ( ) , n2 = str2 . length ( ) ; for ( int i = 0 , j = 0 ; i <= n1 - 1 && j <= n2 - 1 ; i ++ , j ++ ) { if ( str1 . charAt ( i ) != str2 . charAt ( j ) ) { break ; } result += str1 . charAt ( i ) ; } return ( result ) ; }
(method_declaration (modifiers) type: (type_identifier) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier)) (formal_parameter type: (type_identifier) name: (identifier))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list))) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal))) right: (binary_expression left: (identifier) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) update: (update_expression (identifier)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) consequence: (block (break_statement))) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))) (return_statement (parenthesized_expression (identifier)))))