HIDDEN CODES
PROBLEM
A set of code words and a text are given. The text is supposed to contain a message made up of the code words
embedded in the text in a peculiar (and possibly ambiguous) way.
The code words and the text are sequences made up of the upper and lower case letters of the English alphabet
only. Case-sensitivity is assumed. The length of a code word is defined in the usual way: For example, the code
word ALL has length 3.
The letters of a code word do not have to occur consecutively in the given text. For example, the code word ALL will
always occur in the text within a subsequence in the form of Au LvL where u and v denote arbitrary (possibly empty)
sequences of letters. We say that AuLv L is a covering sequence for ALL. In general, a covering sequence for a
code word is defined as a subsequence of the text such that the first letter and the last letter of the subsequence are
the same as those of the code word and it is possible to obtain the code word by deleting some (possibly none) of the
letters of the subsequence. It should be noted that a code word may occur within one or more covering sequences or
may not occur in the text at all, and that a covering sequence may be a covering sequence for more than one code
word.
A covering sequence is identified by its start position (position of its first letter) and its end position (position of its last
letter) in the text. (The first letter of the text is at position 1.) We say that two covering sequences, say c 1 and c 2, do
not overlap if the start position of c 1 is greater than (>) the end position of c 2 or vice versa. Otherwise we say that the
two covering sequences overlap.
To extract the message hidden in the text you undertake the task of forming a solution. A solution is a set of items,
each consisting of a code word and a covering sequence for this code word, so that the following conditions are all
satisfied:
a.
the covering sequences do not overlap with each other;
b.
a covering sequence does not exceed 1000 in length;
c.
the sum of the lengths of the code words is maximal. (Each item contributes the length of the code word it
contains to the sum.)
In case there are more than one solution you are required to report only one solution.
ASSUMPTIONS
•
1 £ N £ 100 where N is the number of code words.
•
The maximum length of a code word is 100 letters.
•
1 £ length of the given text £ 1,000,000 letters.
•

•
We say that a covering sequence c for a code word w is right-minimal if no proper prefix of c (a proper
prefix of c is an initial subsequence of c that is not equal to c) is a covering sequence for w. For example, for the
code word ALL, AAALAL is a right-minimal covering sequence whereas AAALALAL is also a covering
sequence, but not right-minimal.
It is guaranteed that in the given text
a.
for each position in the text the number of right-minimal covering sequences containing that position does not
exceed 2500;
b.
the number of right-minimal covering sequences does not exceed 10,000.

EXAMPLE

words.inp:
4
RuN
RaBbit
HoBbit
StoP
text.inp:
StXRuYNvRuHoaBbvizXztNwRRuuNNP
codes.out:
12
2 9 21
1 4 7
1 24 28
(Remark: The hidden message that could be extracted from the solution is "RuN RaBbit RuN". (An alternative
solution would yield "RuN HoBbit RuN"). Be reminded that the message is not to appear on the output. )
EVALUATION
Your program will be allowed to run 10 seconds.
No partial credit can be obtained for a test case.

There are two input text files: words.inp and text.inp. The words.inp file contains a list of code words and text.inp
contains the text.
•
The first line of words.inp contains the value of N. Each of the following N input lines contains a code word
which is a sequence of letters without any blank in between. The code words are identified by their order of
appearance in the words.inp file: Integers 1 through N serve as the id-numbers for the code words.
•
The text.inp file consists of a sequence of letters (terminated by an end-of-line character followed by the end-of-
file symbol). This file does not include blanks.
RECOMMENDATION FOR PASCAL PROGRAMMERS
You are advised to declare the input file type as text, as opposed to a typed file for reasons of efficiency.

The output must be a text file named codes.out.
•
The first line will contain the sum obtained by your solution.
•
Each of the following lines will determine an item in your solution: The line consists of three integers i, s, e.
Here i is the id-number of the code word that occurs within the covering sequence identified by the start
position s and end position e. The order of the output lines that follow the first line is not important.

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출처 IOI 1999