e message, and then the following menu

will appear that will enable the user to benefit from the system.

When the program starts, it will begin with a high$-$precision clock that measures index creation time and displays the

time spent creating an index data structure. Index creation duration will be printed within the title bar of the menu.

Simple Document Retrieval System

$(30$ Minutes$)$

$1.$ Enter a single keyword to list the document$($s$)($file names$)$

$2.$ Print the top $10$ words that appeared most frequently

$3.$ Print the top $10$ words that appeared least frequently

$4.$ Exit

Option:

Design Guidelines

While reading text files$($or documents$)$:

$$ Lowercase all words,

$$ Get all words, where a word is a string of alpha characters terminated by a non$-$alpha character $($white space

is not alpha$).$ The alpha characters are defined to be $[$a$-$z$].$ Therefore, the sequence of characters for the words

$$apple$+78$&$^+$orange$$ would be $$apple$$ and $$orange$.$

Limitations and Assumptions

$1.$ The collection of documents is closed $($content and number of documents are fixed and will never change$).$

$2.$ Each document is stored in a single text file. Hence, if there are $10,000$ documents, there are $10,000$ text files.

$($Collection of documents is provided on the web online$)$

Figure $1$ and Figure $2$ summarize the aim of this project.

File Name

$($or Document $)$ Content of File

$1.$txt Pease porridge hot, pease porridge cold.

$2.$txt Pease porridge in the pot.

$3.$txt Nine days old.

$4.$txt Some like it hot, some like it cold.

$5.$txt Some like it in the pot.

$6.$txt Nine days old.

Figure $1$: Small set of files and their content.

Figure $2$: Text Files $($ Documents$)$ are Indexed by their word contents.

Since we may not easily estimate the number of words among all documents, one possible solution would be to use

linked lists to maintain a list of words. Also, for each word, a list of files needs to be kept; the number of documents$($or

files$)$ may not be estimated again, then the use of the linked list is suggested.

Head

File Name

$($or Document $)$ Content of File

$1.$txt Pease porridge hot, pease porridge cold.

$2.$txt Pease porridge in the pot.

$3.$txt Nine days old.

$4.$txt Some like it hot, some like it cold.

$5.$txt Some like it in the pot.

$6.$txt Nine days old.

Term File

Name

cold $1,4$

days $3,6$

hot $1,4$

in $2,5$

it $4,5$

like $4,5$

nine $3,6$

old $3,6$

pease $1,2$

porridge $1,2$

pot $2,5$

some $4,5$

the $2,5$

cold days hot like porridge

$1$

$4$

$3$

$6$

$1$

$4$

$4$

$5$

$1$