Commit graph

72 commits

Author SHA1 Message Date
William Carroll
47a11b76a2 Solve InterviewCake's balanced-binary-tree problem
Write a predicate for determining if a binary tree is "super balanced", which
means that the depths of all of the tree's leaves are equal or differ by at most
one.
2020-03-14 12:48:37 +00:00
William Carroll
0f82a527de Mark duplicate InterviewCake questions as DONE
I wrongfully assumed that the relationship between a question and a question
category was one-to-one; it is actually one-to-many. This explains why I
completed the "Cafe Order Checker" and "Top Scores" questions twice.

I'm marking the questions that I've completed as DONE because I would prefer to
do every question once and then prioritize repeating the questions with which I
experienced difficulty.
2020-03-14 12:20:43 +00:00
William Carroll
bd67b07f52 Add default value for pkgs parameter in shell.nix
Commands like `nix-shell shell.nix` couldn't resolve `pkgs` without a default
value. I'm unsure how I expected this to work previously...
2020-03-13 16:52:40 +00:00
William Carroll
a2a5a62836 Solve InterviewCake's top-scores problem
Write a function to sort a list of scores for a game in linear time. While I had
previously solved this in python, I hadn't marked the todo.org file, so I ended
up doing this again.

"Perfect practice makes perfect."
2020-03-13 16:51:38 +00:00
William Carroll
452a8fd4c7 WIP: Partially solve InterviewCake's find duplicate number
Write a function that finds one duplicate number from a list of numbers 1..n.

The function should satisfy the following performance objectives:
Runtime complexity: O(n*log(n))
Space complexity:   O(1)
2020-03-10 15:01:30 +00:00
William Carroll
58ed992059 Solve InterviewCake's "find rotation point" problem
Write a function that accepts a rotated cycle of alphabetically sorted strings
and returns the index what should be the first element if the elements were not
rotated.
2020-03-10 13:27:11 +00:00
William Carroll
b04b1dafd2 Implement an in-place shuffling algorithm
I believe this may be the Fisher-Yates shuffle, but I'm not sure.
2020-03-06 18:45:55 +00:00
William Carroll
549e56186b Solve InterviewCake's product-of-other-numbers
This problem challenged me: without using division, write a function that maps a
list of integers into a list of the product of every integer in the list except
for the integer at that index.

This was another greedy algorithm. The take-away is to first solve the problem
using brute force; this yields an algorithm with O(n*(n-1)) time
complexity. Instead of a quadratic time complexity, a linear time complexity can
be achieved my iterating over the list of integers twice:
1. Compute the products of every number to the left of the current number.
2. Compute the products of every number to the right of the current number.

Finally, iterate over each of these and compute lhs * rhs. Even though I've
solved this problem before, I used InterviewCake's hints because I was stuck
without them.

I should revisit this problem in a few weeks.
2020-03-02 16:45:15 +00:00
William Carroll
b4689761d9 Solve InterviewCake's highest-product-of-3
Write a function that returns the highest product of three integers within a
list of integers. This solution uses a greedy algorithm that solves for the
answer in linear time. The space complexity is constant.
2020-03-01 22:32:25 +00:00
William Carroll
dff621922c Remove HTML-encoded quote
Prefer ' to '
2020-03-01 22:32:25 +00:00
William Carroll
4d2d19f136 Solve InterviewCake's stock-price problem
Write a function that returns the maximum profit that a trader could have made
in a day. I solved this using a greedy algorithm which constantly sets the
maximum profit by tracking the lowest price we've encountered.
2020-03-01 22:32:25 +00:00
William Carroll
d2aa66a5b1 Solve InterviewCake's top-scores
Using a counting sort to sort a list of values in linear time.
2020-03-01 22:32:24 +00:00
William Carroll
e4cdb5daed Solve InterviewCake's word-cloud problem
Write a function to count the frequency of words in a sentence. Ignore casing
for words; ignore punctuation.
2020-03-01 22:32:24 +00:00
William Carroll
93d654df77 Solve InterviewCake permutation-palindrome problem
Write a predicate to test whether any permutation of an input string is a
palindrome.
2020-03-01 22:32:24 +00:00
William Carroll
9e0fdd3973 Remove default values for Nix expression parameters
I'm not sure if this commit breaks everything in my monorepo. I think it
will.

Why am I doing this? Perhaps it's a bad idea. I don't fully understand how
readTree works. My ignorance is costing me hours of time spent debugging. In an
effort to better understand readTree, I'm removing the default values for my Nix
expression parameters, which I believe have preventing errors from surfacing.
2020-03-01 22:32:24 +00:00
William Carroll
0dd3987821 Solve InterviewCake's inflight-entertainment problem
Write a predicate that tests whether two films in a list of films can exactly
fill the duration of a flight.
2020-02-21 11:30:01 +00:00
William Carroll
66c38f8656 Solve InterviewCake's cafe-order-checker problem
Write a predicate that tests if a given list of integers, zs, is a possible
interleaving of two other lists, xs and ys.
2020-02-20 15:20:58 +00:00
William Carroll
737bdd0a23 Solve InterviewCake's merge sorted arrays question
Write a function merging two sorted arrays into one sorted array.
2020-02-19 16:02:38 +00:00
William Carroll
ca6bd29ed8 Solve bonus part of reverse-words
InterviewCake asks "How would you handle punctuation?". Without precise specs
about what that entails, I'm supporting sentences ending with punctuation.
2020-02-19 15:01:42 +00:00
William Carroll
acf1b8c4f0 Solve InterviewCake's reverse-words
Wrote a function to reverse the words in a list of characters. A word is a
space-delimited strings of characters.

The trick here is to first reverse the entire string and then reverse each word
individually.
2020-02-19 15:01:42 +00:00
William Carroll
9fa97eab67 Solve merging-ranges
Write a function to merge meeting times. Added an in-place solution, which the
"Bonus" section suggested attempting to solve.

- Added some simple benchmarks to test the performance differences between the
  in-place and not-in-place variants. To my surprise, the in-place solution was
  consistently slower than the not-in-place solution.
2020-02-13 14:52:20 +00:00
William Carroll
fabf1c9334 Tidy up structure of briefcase
I had a spare fifteen minutes and decided that I should tidy up my
monorepo. The work of tidying up is not finished; this is a small step in the
right direction.

TL;DR
- Created a tools directory
- Created a scratch directory (see README.md for more information)
- Added README.md to third_party
- Renamed delete_dotfile_symlinks -> symlinkManager
- Packaged symlinkManager as an executable symlink-mgr using buildGo
2020-02-12 16:58:29 +00:00