static int countSub ( String str ) {
  int [ ] last = new int [ MAX_CHAR ] ;
  Arrays . fill ( last , - 1 ) ;
  int n = str . length ( ) ;
  int [ ] dp = new int [ n + 1 ] ;
  dp [ 0 ] = 1 ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) {
    dp [ i ] = 2 * dp [ i - 1 ] ;
    if ( last [ ( int ) str . charAt ( i - 1 ) ] != - 1 ) dp [ i ] = dp [ i ] - dp [ last [ ( int ) str . charAt ( i - 1 ) ] ] ;
    last [ ( int ) str . charAt ( i - 1 ) ] = ( i - 1 ) ;
  }
  return dp [ n ] ;
}

static int countSub ( String str ) { int [ ] last = new int [ MAX_CHAR ] ; Arrays . fill ( last , - 1 ) ; int n = str . length ( ) ; int [ ] dp = new int [ n + 1 ] ; dp [ 0 ] = 1 ; for ( int i = 1 ; i <= n ; i ++ ) { dp [ i ] = 2 * dp [ i - 1 ] ; if ( last [ ( int ) str . charAt ( i - 1 ) ] != - 1 ) dp [ i ] = dp [ i ] - dp [ last [ ( int ) str . charAt ( i - 1 ) ] ] ; last [ ( int ) str . charAt ( i - 1 ) ] = ( i - 1 ) ; } return dp [ n ] ; }
(method_declaration (modifiers) type: (integral_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier))) body: (block (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (unary_expression operand: (decimal_integer_literal))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (expression_statement (assignment_expression left: (array_access array: (identifier) index: (decimal_integer_literal)) right: (decimal_integer_literal))) (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 (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (decimal_integer_literal) right: (array_access array: (identifier) index: (binary_expression left: (identifier) right: (decimal_integer_literal)))))) (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (cast_expression type: (integral_type) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal)))))) right: (unary_expression operand: (decimal_integer_literal)))) consequence: (expression_statement (assignment_expression left: (array_access array: (identifier) index: (identifier)) right: (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (array_access array: (identifier) index: (array_access array: (identifier) index: (cast_expression type: (integral_type) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))))))))) (expression_statement (assignment_expression left: (array_access array: (identifier) index: (cast_expression type: (integral_type) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal)))))) right: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))))))) (return_statement (array_access array: (identifier) index: (identifier)))))