Problem:
Kanglish : Analysis on Artificial Language

The late Prof. Kanazawa made an artificial language named Kanglish, which is
similar to English, for studying mythology. Words and sentences of Kanglish are
written with its own special characters called "Kan-characters". The size of the
set of the Kan-characters is 38, i.e., there are 38 different Kan-characters in
the set. Since Kan-characters cannot be directly stored in a computer because of
the lack of a coded character set, Prof. Kanazawa devised a way to represent
each Kan-character as an alphabetical letter or an ordered combination of two
alphabetical letters. Thus, each Kan-character is represented as one of the
following 26 letters

"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
"n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", and "z",

or one of the following 12 combinations of letters

"ld", "mb", "mp", "nc", "nd", "ng", "nt", "nw", "ps", "qu", "cw",
and "ts".

In addition, the Kan-characters are ordered according to
the above alphabetical representation. The order is named Kan-order in which the
Kan-character represented by "a" is the first one, that by "b" is the second,
that by "z" is the 26th, that by "ld" is the 27th, and that by "ts" is the 38th
(the last).

The representations of words in Kanglish are separated by spaces. Each
sentence is written in one line, so there are no periods or full stops in
Kanglish. All alphabetical letters are in lower case, i.e., there are no
capitalizations.

We currently have many documents written in Kanglish with the alphabetical
representation. However, we have lost most of Prof. Kanazawa's work on how they
can be translated. To recognize his work, we have decided to first analyze them
statistically. The first analysis is to check sequences of consecutive
Kan-characters in words.

For example, a substring "ic" in a word "quice" indicates an ordered pair of
two adjacent Kan-characters that are represented by "i" and "c". For simplicity,
we make a rule that, in the alphabetical representation of a word, a
Kan-character is recognized as the longest possible alphabetical representation
from left to right. Thus, a substring "ncw" should be considered as a pair of
"nc" and "w". It does not consist of "n" and "cw", nor "n", "c", and "w".

For each Kan-character, there are 38 possible pairs of that Kan-character and
another Kan-character, e.g. "aa", "ab", ..., "az", "ald", ..., "ats". Thus,
mathematically, there is a total of 1444 (i.e., 38x38) possible pairs, including
pairs such as "n" and "cw", which is actually not allowed according to the above
rule.

Your job is to write a program that counts how many times each pair occurs in
input data. For example, in the sentence

qua ist qda quang quice

the Kan-character represented by "qu" appears
three times. There are two occurrences of the pair of "qu" and "a", and one
occurrence of the pair of "qu" and "i". Note that the alphabetical letter "q"
appears four times in the example sentence, but the Kan-character represented by
"q" occurs only once, because "qu" represents another Kan-character that is
different from the Kan-character represented by "q".

For simplicity, a newline at the end of a line is considered as a space. Thus
in the above example, "e" is followed by a space.

Input

n
line1
line2
...
linen

The first line of the input is an integer n, which indicates the
number of lines that follow. Each line except for the first line represents one
Kanglish sentence. You may assume that n <= 1000 and that each line
has at most 59 alphabetical letters including spaces.

Output

a kc1 m1
b kc2 m2
c kc3 m3
...
ts kc38 m38

The output consists of 38 lines for the whole input lines. Each line of the
output has two strings and an integer. In the i-th line in the output,
the first string is the alphabetical representation of the i-th
Kan-character in the Kan-order. For example, the first string of the first line
is "a", that of the third line is "c", and that of the 37th line is "cw". The
first string is followed by a space.

The second string in the i-th line (denoted by kci
above) shows the alphabetical representation of a Kan-character that most often
occurred directly after the first Kan-character. If there are two or more such
Kan-characters, the first one in the Kan-order should be printed. The second
string is followed by a space.

The integer (denoted by mi above) in the i-th line
shows the number of times that the second Kan-character occurred directly after
the first Kan-character. In other words, the integer shows the number of times
that ``the ordered pair of the first Kan-character and the second
Kan-character'' appeared in the input. The integer is followed by a newline.

Suppose the 28th output line is as follows:

mb e 4

"mb" is output because it is the 28th character in
the Kanglish alphabet. "e 4" means that the pair "mbe" appeared 4 times in the
input, and that there were no pairs beginning with "mb" that appeared more than
4 times.

Note that if the i-th Kan-character does not appear in the input, or
if the i-th Kan-character is not followed by any other Kan-characters but
spaces, the second string in the i-th output line should be "a" and the
third item should be zero.

Although the output does not include spaces, Kan-characters that appear with
a space in-between is not considered as a pair. Thus, in the following example

abc def

"d" is not counted as occurring after "c".

Sample Input

3
nai tiruvantel ar varyuvantel i valar tielyama nu vilya
qua ist qda quang ncw psts
svampti tsuldya jay quadal ciszeriol

Output for the Sample Input

a r 3
b a 0
c i 1
d a 2
e l 3
f a 0
g a 0
h a 0
i s 2
j a 1
k a 0
l y 2
m a 1
n a 1
o l 1
p a 0
q d 1
r i 1
s t 1
t i 3
u v 2
v a 5
w a 0
x a 0
y a 3
z e 1
ld y 1
mb a 0
mp t 1
nc w 1
nd a 0
ng a 0
nt e 2
nw a 0
ps ts 1
qu a 3
cw a 0
ts u 1

Solution in Ruby (judge verdict: Accepted)

### constant

K2CHS = ["ld", "mb", "mp", "nc", "nd", "ng", "nt", "nw", "ps", "qu", "cw", "ts"]
K1CHS = ('a'..'z').to_a
KCHS = K1CHS + K2CHS

### subroutines

def split_word(word)
  chs = []
  i = 0
  wlen = word.length
  while i < wlen
    ch2 = word[i, 2]
    if $kcodes[ch2]
      chs << ch2
      i += 2
      next
    end
    chs << word[i]
    i += 1
  end
  chs
end

### main

$kcodes = {}
KCHS.each_with_index{|c, i| $kcodes[c] = i}
#p $kcodes; exit

pairs = KCHS.map{KCHS.map{0}}

n = gets.to_i

n.times do
  for word in gets.strip.split
    pcc = nil
    for ch in split_word(word)
      cc = $kcodes[ch]
      if ! pcc.nil?
        pairs[pcc][cc] += 1
      end
      pcc = cc
    end
  end
end

for pcc in (0...KCHS.length)
  max_pn = 0
  max_cc = 0

  for cc in (0...KCHS.length)
    pn = pairs[pcc][cc]
    if max_pn < pn
      max_pn = pn
      max_cc = cc
    end
  end

  puts [KCHS[pcc], KCHS[max_cc], max_pn].join(' ')
end