#P12900. [NERC 2020] ASCII Automata Art
[NERC 2020] ASCII Automata Art
题目描述
This problem statement is quite wordy by itself and does not need a legend. You are given a regular expression and your task is to render its corresponding automaton as an ASCII art text drawing following the specification in the problem statement. Please, see examples.
A regular expression in this problem consists of uppercase letters from A
to Z
, special characters +
, ?
, *
, and parenthesis that are used for grouping. An input to the problem is given by an <input>
non-terminal of the following BNF grammar:
<input> ::= <expr>
<expr> ::= <term> | <term> `|' <expr>
<term> ::= <atom> | <atom><term> | <term><atom>
<atom> ::= <letter> | `(' <expr> `)' | <atom> `+' | <atom> `?' | <atom> `*'
<letter> ::= `A' | `B' | ... | `Z'
A regular expression is rendered as an ASCII art picture using the precise rules that are given below. They recursively define a unique representation for each regular expression as a rectangular box of characters with the specified number of rows and columns. Empty characters of the representation, including trailing ones, must be filled with spaces.
A <term>
that consists of a sequence of uppercase letters is rendered as a box of 3 rows and columns using +
and -
characters to render a border on the first and the last rows and columns as shown in the example. The production rule for the <term>
non-terminal in the grammar is intentionally ambiguous. The longest possible sequence of adjacent <letter>
non-terminals in the regular expression must be grouped into a <term>
and rendered as a single box.
For example, a <term>
of NERC
is rendered as the following box:
+------+
+ NERC +
+------+
A <term>
that consists of a sequence of <atom>
non-terminals and <term>
non-terminals with letters (as described above) is rendered by laying out the constituent boxes left-to-right, aligned vertically to the top, with 2 columns separating adjacent boxes. The height of the resulting box is equal to the maximum height of the constituent boxes.
Each pair of adjacent boxes is joined by rendering ->
characters on the 2nd row in the columns between them.
For example, a <term>
of N(E)RC
(consisting of a sequence: <atom>
of A
, <atom>
of (E)
, and a letters-only <term>
of RC
)
is rendered as the following box:
+---+ +---+ +----+
+ N +->+ E +->+ RC +
+---+ +---+ +----+
An <expr>
that consists of a single <term>
is rendered as its <term>
.
An <expr>
that consists of a |
-separated sequence of <term>
non-literals is rendered by laying out the corresponding <term>
boxes top-to-bottom, aligned to the left, with a single row separating adjacent <term>
boxes. The width of the resulting box is equal to the maximum width of the <term>
boxes plus 6. There are 3 additional columns on the left, and 3 on the right. The first column and the last column use +
and |
characters to join the 2nd rows of all the <term>
boxes from the top to the bottom one, with +
placed on the 2nd row of each <term>
box. The 2nd and the 3rd columns on the left and the 3rd-to-last and the 2nd-to-last columns on the right have ->
characters on the 2nd rows of the corresponding <term>
boxes. Additionally, shorter <term>
boxes are connected on the right with extra -
characters on their 2nd rows.
For example, an <expr>
of C|ON|TEST
is rendered as the following box:
+---+
+->+ C +---->+
| +---+ |
| |
| +----+ |
+->+ ON +--->+
| +----+ |
| |
| +------+ |
+->+ TEST +->+
+------+
An <atom>
of (
<expr>
)
is rendered as its <expr>
.
An <atom>
of <atom>
+
is rendered as a box of its source <atom>
with 2 additional rows at the bottom and 6 additional columns (3 on the left and 3 on the right). The first and the last columns, starting with the 2nd row, and the last row are filled with the connecting characters as shown in the example.
- The 2nd row starts with
+->
and ends with->+
to connect to the 2nd row of the source<atom>
box. - The last row starts with
+<-
to represent a backwards edge in the automaton.
For example, an <atom>
of A+
is rendered as the following box.
+---+
+->+ A +->+
| +---+ |
| |
+<--------+
An <atom>
of <atom>
?
is rendered as a box of its source <atom>
with 3 additional rows at the top and 6 additional columns (3 on the left and 3 on the right). The first and the last columns (from the 2nd to the 5th row) and the 2nd row are filled with the connecting characters as shown in the example.
- The first row of
<atom>
?
is always empty (filled with spaces). - The 2nd row ends with
->+
to represent an epsilon-edge in the corresponding automaton. - The 5th row starts with
+->
and ends with->+
to connect to the 2nd row of the source<atom>
box.
For example, an <atom>
of B?
is rendered as the following box.
+-------->+
| |
| +---+ |
+->+ B +->+
+---+
An <atom>
of <atom>
*
is rendered as a box of its source <atom>
with 5 additional rows (3 at the top and 2 at the bottom) and 6 additional columns (3 on the left and 3 on the right). The first and the last columns, with the 2nd and the last row, are filled with the connecting characters as shown in the example.
- The first row of
<atom>
*
is always empty (filled with spaces). - The 2nd row ends with
->+
to represent an epsilon-edge in the corresponding automaton. - The 5th row starts with
+->
and ends with->+
to connect to the 2nd row of the source<atom>
box. - The last row starts with
+<-
to represent a backwards edge in the automata.
For example, an <atom>
of C*
is rendered as the following box.
+-------->+
| |
| +---+ |
+->+ C +->+
| +---+ |
| |
+<--------+
An <input>
is rendered as a box that has 6 more columns than the corresponding box of the <expr>
, with 3 additional columns on the left, and 3 on the right. The 2nd row starts with S->
to represent the starting state of the automaton and ends with ->F
to represent the final state of the automaton. See the example output.
输入格式
The input consists of a single line that corresponds to the non-terminal of the grammar given the problem statement and has at most 100 characters in length.
输出格式
On the first line of the output, write two integers and --- the height and the width, correspondingly, of the box that corresponds to the given . On each of the next lines, write characters of the corresponding ASCII art rendering.
NE?(ER)C++|(IS)*?|(CHA((LL))ENGING)
23 57
+---+ +----+ +---+
S->+->+ N +->+-------->+->+ ER +->+->+->+ C +->+->+->+->F
| +---+ | | +----+ | | +---+ | | |
| | +---+ | | | | | |
| +->+ E +->+ | +<--------+ | |
| +---+ | | |
| +<--------------+ |
| |
| |
+->+--------------->+---------------------------->+
| | | |
| | | |
| +->+--------->+->+ |
| | | |
| | +----+ | |
| +->+ IS +->+ |
| | +----+ | |
| | | |
| +<---------+ |
| |
| +-----+ +----+ +--------+ |
+->+ CHA +->+ LL +->+ ENGING +------------------->+
+-----+ +----+ +--------+