Exercises

1) Variables and Print 2) Functions 3) Control structures 4) Arrays 5) File 6) Text processing 7) Misc

For some questions, Ruby program with raise statements is provided to automatically test your solution in the exercise_files directory
You can also solve these exercises on repl.it, with an option to submit them for review
- or use gitter group chat for discussion

1) Variables and Print

Q1a) Ask user information, for ex: name, department, college etc and display them using print function

# Sample of how program might ask user input and display output afterwards
$ ./usr_ip.rb 
Please provide the following details
Enter your name: learnbyexample
Enter your department: ECE
Enter your college: PSG Tech

------------------------------------
Name       : learnbyexample
Department : ECE
College    : PSG Tech
------------------------------------

2) Functions

Q2a) Write a function to return length of integer numbers

>> len_int(962306349871524124750813401378124)
=> 33
>> len_int(+42)
=> 2
>> len_int(-42)
=> 2

# len_int('a') should give
TypeError (provide only integer input)

Q2b) Compare if two strings are same irrespective of case

>> str_cmp('nice', 'nice')
=> true
>> str_cmp('how', 'who')
=> false
>> str_cmp('GoOd DaY', 'gOOd dAy')
=> true
>> str_cmp('foo', 'food')
=> false

Q2c) Compare if two strings are anagrams (assume input consists of ASCII alphabets only)

>> str_anagram('god', 'Dog')
=> true
>> str_anagram('beat', 'table')
=> false
>> str_anagram('Tap', 'paT')
=> true
>> str_anagram('beat', 'abet')
=> true
>> str_anagram('seat', 'teal')
=> false

Q2d) Write a function to return corresponding integer or floating-point number for given number/string input

# number input
>> num(3)
=> 3
>> num(0x1f)
=> 31
>> num(3.32)
=> 3.32

# string input
>> num('123')
=> 123
>> num('-78')
=> -78
>> num(" 42  \n ")
=> 42
>> num('3.14')
=> 3.14
>> num('3.982e5')
=> 398200.0

>> s = '56'
=> "56"
>> num(s) + 44
=> 100

Raise exception if input is not valid or if the input cannot be converted to a number

# num(['1', '2.3'])
TypeError (not a valid input)

# num('foo')
ArgumentError (could not convert string to int or float)

3) Control structures

Q3a) Write a function that returns

'Good' for numbers divisible by 7
'Food' for numbers divisible by 6
'Universe' for numbers divisible by 42
'Oops' for all other numbers
Only one output, divisible by 42 takes precedence

>> six_by_seven(66)
=> "Food"
>> six_by_seven(13)
=> "Oops"
>> six_by_seven(42)
=> "Universe"
>> six_by_seven(14)
=> "Good"
>> six_by_seven(84)
=> "Universe"
>> six_by_seven(235432)
=> "Oops"

bonus: use a loop to print number and corresponding string for numbers 1 to 100

1 Oops
2 Oops
3 Oops
4 Oops
5 Oops
6 Food
7 Good
...
41 Oops
42 Universe
...
98 Good
99 Oops
100 Oops

Q3b) Write a function that

accepts two integers
for all integers in the range defined by them, find all numbers that are simultaneously palindromes in decimal, binary and octal representations - for example, 585 is palindrome in all three representations
return the result as array of arrays
first array should contain pairs of decimal and binary numbers
second array should contain groups of decimal, binary and octal numbers

>> num_palindrome(6, 20)
=> [[["7", "111"], ["9", "1001"]], [["7", "111", "7"], ["9", "1001", "11"]]]
>> num_palindrome(300, 600)
=> [[["313", "100111001"], ["585", "1001001001"]], [["585", "1001001001", "1111"]]]

4) Arrays

Q4a) Write a function that returns product of all numbers of an array/range

>> product([1, 4, 21])
=> 84
>> product([-4, 2.3e12, 77.23, 982, 0b101])
=> -3.48863356e+18
>> product([-3, 11, 2])
=> -66
>> product([8, 300])
=> 2400
>> product([234, 121, 23, 945, 0])
=> 0
>> product(1..5)
=> 120

Q4b) Write a function that returns nth lowest of an array/string. Return the lowest if second argument is not specified

Note that duplicates shouldn't affect determining nth lowest

>> nums = [42, 23421341, 234.2e3, 21, 232, 12312, -2343]
=> [42, 23421341, 234200.0, 21, 232, 12312, -2343]
>> nth_lowest(nums, 3)
=> 42
>> nth_lowest(nums, 5)
=> 12312

>> nums = [1, -2, 4, 2, 1, 3, 3, 5]
=> [1, -2, 4, 2, 1, 3, 3, 5]
>> nth_lowest(nums)
=> -2
>> nth_lowest(nums, 4)
=> 3

>> nth_lowest('unrecognizable', 3)
=> "c"
>> nth_lowest('jump', 2)
=> "m"
>> nth_lowest('abracadabra', 5)
=> "r"

Q4c) Write a function that accepts a string input and returns slices

if input string is less than 3 characters long, return an array with input string as the only element
otherwise, return array with all string slices greater than 1 character long
order of slices should be same as shown in examples below

>> word_slices('i')
=> ["i"]
>> word_slices('to')
=> ["to"]

>> word_slices('are')
=> ["ar", "are", "re"]
>> word_slices('table')
=> ["ta", "tab", "tabl", "table", "ab", "abl", "able", "bl", "ble", "le"]

5) File

Q5a) Print sum of all numbers from a file containing only single column numbers (integer or float)

$ cat f1.txt 
8
53
3.14
84
73e2
100
2937

$ ./col_sum.rb 
10485.14

Q5b) Print sum of all numbers (assume only positive integer numbers) from a ASCII encoded file containing arbitrary string

$ cat f2.txt 
Hello123 World 35
341 2
Good 13day
How are 1784 you

$ ./extract_sum.rb 
2298

Q5c) Sort file contents in alphabetic order based on each line's extension

extension here is defined as the string after the last . in the line
if line doesn't have a ., those lines should come before lines with .
sorting should be case-insensitive
use rest of string as tie-breaker if there are more than one line with same extension
assume input file is ASCII encoded and small enough to fit in memory

bonus: instead of printing results to stdout, change the input file itself with sorted result

$ cat f3.txt
power.Log
foo.123.txt
list
report_12.log
baz.TXT
hello.RB
loop.do.rb
Fav_books

$ ./sort_by_ext.rb
Fav_books
list
power.Log
report_12.log
hello.RB
loop.do.rb
baz.TXT
foo.123.txt

6) Text processing

Q6a) Check if two words are same or differ by only one character (irrespective of case), input strings should have same length

7) Misc

Q7a) Write a function that

accepts a filesystem path(default) or a url(indicated by true as second argument)
returns the longest word(here word is defined as one or more consecutive sequence of alphabets of either case)
assume that input is small enough to fit in memory and that there's only one distinct longest word

>> ip_path = 'poem.txt'
=> "poem.txt"
>> longest_word(ip_path)
=> "Violets"

>> ip_path = 'https://www.gutenberg.org/files/60/60.txt'
=> "https://www.gutenberg.org/files/60/60.txt"
>> longest_word(ip_path, true)
=> "misunderstandings"

More to come

Exercises

Exercises

1) Variables and Print

2) Functions

3) Control structures

4) Arrays

5) File

6) Text processing

7) Misc

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