on 11-Oct-2018 (Thu)

Question

In python, why would you use the array datatype (from the array module) instead of a simple list?

Answer

If you are dealing with an array of all items of the same type (e.g. all ints) and you want to save space/memory.

Question

In regular expressions, the [...] charactor signifies exactly one of any charactors except line break (e.g. a [...] c matches abc, adc, etc)

Answer

"."

Question

In Linux, if you are doing a file search with grep, how do you make sure you are searching for whole word only, "this" in file test.txt (i.e. "this is it" line will match but "thisis is it" will not")?

Answer

grep -w 'this' test.txt

Question

In regular expressions, how do you search for a match for whole word starting with "a", followed by any single letter from "b" to "d", followed by "g"? (use grep to search for this pattern in file test.txt)

Answer

grep -w 'a[b-d]g' test.txt

Question

In Linux, grep stands for [...] and is a tool to search, line by line, in a file for string matches.

Answer

global regular expression print

Question

In regular expressions, search for whole words that start with "a", followed by zero or more chars between "d" to "g", and end with "z" (use grep as example to search in file test.txt)?

Answer

grep -w 'a[d-g]*z' test.txt
^^ note the * that comes right after [d-g]

Question

In regular expressions, using grep, match for the words kremlin, krypton, krn, krzn, in file test.txt?

Answer

grep -w 'kr.*n' test.txt
^^ note the use of "." followed by "*" to search for 0 or more of any char

Question

In Linux, the [...] character has different usage in file path matching vs grep, as in file path mathing it does NOT have to be preceded by another char like "." but in grep it does have to be.

Answer

"*"

Question

In regular expressions, what is the difference between square brackets "[]" vs round brackets "()"?

Answer

Square brackets means one of serveral charactors (e.g. [a-e]) whereas round brackets means one of serveral words (e.g. (the|this) )

Question

In regular expressions, using grep, search for words that start with "sh" or "th" and end in "rt" (e.g. shirt, short, and thwart) in document test.txt?

Answer

grep -w '(sh|th).*rt' test.txt
^^ note the use of "|" for or, and the use of round brackets for matching words.

Question

In regular expressions, using grep, match for words that start with "thr", followed by zero or more vowels, and ending in t (e.g. threat and throat) in file test.txt?

Answer

grep -w 'thr[aeiou]*t' test.txt
^^ not the use of [aeiou] to match for any one of the included chars that are vowels

Question

In regular expressions, using grep, match for all words that start with "the", followed by zero or more non-vowels, and ending in "t" (e.g. "theft" matches but "theit" does not), in file test.txt?

Answer

grep -w 'the[^aeiou]*t' test.txt
^^ note the use of "^" char to match for all chars except vowels

Question

In regular expressions, using grep, search for all lines that begin with the word "The", in file test.txt

Answer

grep '^The' test.txt
^^ note the use of "^", also accaptable is: grep ' *^The' test.txt, this is to cover leading whitespace

Question

In regular expressions, using grep, search for all the lines that end with the word "hack" (may be followed by some whitespace), in file test.txt?

Answer

grep 'hack *$' test.txt
^^ note the use of $, also note the " *" do count for whitespace

Question

In regular expressions, for example using grep, 'myfile.txt' will match both "myfileqtxt" and "myfile.txt", how do you make it just match "myfile.txt"?

Answer

grep 'myfile\.txt'
^^ i.e. use the escape char "\" before the special char "."

Question

In Linux, if you want to search in files and use regex features such as (+ ? \< \> ( ) | ) characters, you must use the [...] flag of grep

Answer

-E
^^ -E is short for --extended-regexp, note that grep -E is same as egrep (depricated)

Question

In Linux, if you want to just search for string literals in a file and not have to worry about using the "\" escape character, you can use the [...] flag of grep

Answer

-F
^^ -F is short for --fixed-strings, and is same as fgrep (depricated)

Question

In regular expressions, using grep, search for lines that have words that end with 100 "i"s, in file test.txt (do it in easy way without typing in 100 "i"s)?

Answer

grep -w '.*i\{100\}' test.txt
^^ note the i\{100\}

Question

In regular expressions, using grep, search for all lines in file test.txt that have words that end with 5 to 10 "i"'s?

Answer

grep -w '.*i\{5,10\}' test.txt
^^ note the i\{5,10\} syntax

Question

In regular expressions, using grep, search for all lines in a file test.txt, that have words ending with 7 or more vowels?

Answer

grep -w '.*[aeiou]\{7,\}' test.txt
^^ note the syntax \{7,\}

Question

In regular expressions, the [...] charactor represents one or more occurences of something (as opposed to * being 0 or more occurances of something).

Answer

+

Question

In regular expressions, the [...] charactor represents 0 or 1 occurences of something.

Answer

?

Question

In regular expressions, what syntax do you use to match whole words (this is an alternative to the grep -w flag)?

Answer

\<\>

Question

In algorithms, the [...] algorithm involves breaking a problem into smaller independent sub problems, and then in some way combining the results to obtain a global solution.

Answer

divide and conquer

Question

In algorithms, [...] algorithm can be used when the problem can be devided into subproblems that overlap and where intermediate results are cached and can be used in subsequent operations.

Answer

dynamic programming

Question

In algorithms, [...] algorithms involve finding the best solution to a local problem in the hope that this will lead to a global solution (the classic example is applying it to the shortest path problem, where this approach always chooses the closest destination first).

Answer

greedy

Question

In algorithms, divide and conquer (and dynamic programming) algorithms often use [...]

Answer

recursion

Question

In algorithms, a recursive function has two types of cases: [...] , which tell the recursion when to terminate, and recursive case that calls itself while going towards the base case.

Answer

base case

Question

In algorithms, a recursive function has two types of cases: base cases, which tell the recursion when to terminate, and [...] cases that calls itself while going towards the base case.

Answer

recursive

Question

In algorithms, explain what is the base case of a recursive function?

Answer

It is the terminating case that solves the simplest sub problem of the recursion

Question

In algorithms, recursive funtions have a base case and a recursive case, the recursive case does two things, 1) it calls the function itself and 2) [...]

Answer

it moves the solution closer to the base case

Question

In algorithms, between recursion and iteration, which is more memory intensive (hint: the one that results in stack overflow if fails to terminate).

Answer

recursion

Question

In algorithms, between recurtion and iteration, which one is usually more processor intensive (hint: thing of case where it fails to terminate/is infinite)?

Answer

interation

Question

In algorithm, time complexity is measured in [...] notation

Answer

big-O
^^ FYI, O stands for Order-magnitude

Question

In algorithms, the big-O time complexity order from fastest to slowest is: [...] , O(logn), O(n), O(nLogn), O(n^2), O(n^3), O(2^n)

Answer

O(1)

Question

In algorithms, the big-O time complexity order from fastest to slowest is: O(1) , [...] , O(n), O(nLogn), O(n^2), O(n^3), O(2^n)

Answer

O(logn)

Question

In algorithms, the big-O time complexity order from fastest to slowest is: O(1) , O(logn), [...] , O(nLogn), O(n^2), O(n^3), O(2^n)

Answer

O(n)

Question

In algorithms, the big-O time complexity order from fastest to slowest is: O(1) , O(logn), O(n), [...] , O(n^2), O(n^3), O(2^n)

Answer

O(nLogn)

Question

In algorithms, the big-O time complexity order from fastest to slowest is: O(1) , O(logn), O(n), O(nLogn), [...] , O(n^3), O(2^n)

Answer

O(n^2)

Question

In algorithms, the big-O time complexity order from fastest to slowest is: O(1) , O(logn), O(n), O(nLogn), O(n^2), [...] , O(2^n)

Answer

O(n^3)

Question

In algorithms, the big-O time complexity order from fastest to slowest is: O(1) , O(logn), O(n), O(nLogn), O(n^2), O(n^3), [...]

Answer

O(2^n)

Question

In algorithms, appending to the end of a list, or looking up something in a dictionary by key, is of what big-O time complexity?

Answer

O(1)

Question

In algorithms, what is the big-O time complexity of an algorithm that shrinks the input size in half on each iteration (e.g. finding an element in a sorted array)?

Answer

O(logn)
^^ note that logn is, log base2 n