Algorithms and Programming
Laboratory number 06
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Exercise 01 (A, B, C)
Extension of Exercise 01, Laboratory 03
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A text of unknown length, but whose rows are limited to 1000
characters, is stored in a file.

Write a C application able to evaluate the absolute frequency of all
strings which appear in the file.

More specifically the program has to:
* Receive on the command line two file names (the input and the output
  file, respectively).
* Read the input file and store all words in a list.
  Each node of the list must contain the string and its absolute
  frequency within the input file.
  Capital and small letters have to be considered as equivalent
  (i.e., "WORD", "Word", and "word" are the same string).
* Store the list into the output file.

The list may be manipulated using:
1. Head insertions.
   In this way the string order within the file will be inverted into
   the list.
2. Tail insertions (using a list with a tail pointer with or without a
   circular implementation).
   In this way the string order within the file will be maintained into
   the list.
3. Ordered insertion (into an ordered list).
   In this way the string order within the file will be reorder into
   the list in alphabetic order.
You can choose to implement version A, B, or C or all of them.

Example
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This is a correct input file

Mi illumino di immenso
Illumino di immenso
Di immenso
IMMENSO

The output file has to be the following (order depends on the type of
the list selected):

immenso 4
di 3
illumino 2
Mi 1



Exercise 02
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A file contains data on a set of employees.
For each employee there is a row of the file, including:
* Last and first name (a single C string, maximum 50 characters,
  e.g., Smith_John).
* Personal identification (exactly 16 characters).
* Data of hiring (format dd.mm.yyy, e.g, 30.05.2005).
* Salary (integer value, in euro).
Fields are space-separated.
Employees do not appear in any specific order.

A C program receives 3 parameters on the command line:
* Input file name (the format is the previously defined one).
* A single string, representing a last and first name pair (e.g.,
  Clinton_Bill).
* A string made of only + and - characters (e.g., +++---+-+).

The program has to:
* Read the file.
* Store its content in a LIFO-logic list, but with two pointers for
  each element one pointing ahead and one pointing behind the element
  itself as:

  pHead  --> ----- --> ----- --> ----- --> ----- -X
             |###|     |###|     |###|     |###|
          X- ----- <-- ----- <-- ----- <-- -----

* Find in the list the element storing the employee whose name is
  passed on the command line as a second parameter.
* Move along the list in the
  - right direction for each '+' character
  - left direction for each '-' character
  in the third string parameter.
  For each visited node of the list (including the first one) the
  program has to print out (on standard output) all data of the
  employee (with the same format this data appears in the original
  input file).
  If the end of the list is reached (in either side) the program has to
  print-out the same element repeatedly.

Example
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Let the command line parameters be the following

file.txt Giallo_Antonio ---+

and the file be the following

Rossi_Alberto A1B1C1D1E1F1G1H1 03.12.1998 1845
Giallo_Antonio A2B2C2D2E2F2G2H2 13.11.2007 1140
Verdi_Federica A3B3C3D3E3F3G3H3 25.09.1989 2157
Bianchi_Elena A4B4C4D4E4F4G3H4 15.02.2004 1345

The file has to be stored in the LIFO structure as:
Bianchi  ->  Verdi  -> Giallo  -> Rossi  
Then, the program has to:
- find Giallo_Antonio in the list and print its data
- move left on Verdi and print its data (first -)
- move left again and print Bianchi (second -)
- do not move and print Bianchi again (third -)
- move right and print Verdi (first +):

Giallo_Antonio A2B2C2D2E2F2G2H2 13.11.2007 1140
Verdi_Federica A3B3C3D3E3F3G3H3 25.09.1989 2157
Bianchi_Elena A4B4C4D4E4F4G3H4 15.02.2004 1345
Bianchi_Elena A4B4C4D4E4F4G3H4 15.02.2004 1345
Verdi_Federica A3B3C3D3E3F3G3H3 25.09.1989 2157