Commit graph

20618 commits

Author SHA1 Message Date
Vincent Ambo
cce0ad1bcd chore(tazjin/emacs): Minor cleanup of unused modes and config
Change-Id: I38c6a32339bf7606b733a938b4e55df2506a13a7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2107
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI
2020-11-21 13:27:20 +00:00
William Carroll
847aad2a14 Implement the Levenstein "edit distance" algorithm
This is the mother of dynamic programming algorithms in my opinion. It computes
the minimal "edit distance" between two input strings where an edit is
considered one of:
  - inserting a character into `a`
  - deleting a character from `a`
  - substituting a character in `a` with a character from `b`

It took me awhile to grok the algorithm, but I implemented this from my
understanding of something that I read ~3 nights prior, so I must've understood
what I read. Good news!
2020-11-20 21:59:18 +00:00
William Carroll
f652ea0be6 Solve "count islands" problem
This morning, I attended the "Interview Club" and was asked this question by the
interviewer in front of ~20 FTEs. While I struggled to fully solve it during the
abridged (i.e. 20 minute) timeslot, I completed the problem afterwards.

Here is my solution.
2020-11-20 21:32:22 +00:00
William Carroll
fa717e8a6f Re-implement suffix_tree function
Create a suffix tree from an input string. This implementation uses a stack to
control the flow of the program.

I expected this attempt to be easier than my first attempt, but surprisingly, it
was similarly difficult. It took me ~30-45 minutes to successfully implement
this function, and I'm still not pleased with the final result.
2020-11-19 21:12:36 +00:00
William Carroll
1088e4143d Implement a suffix tree
While it took me awhile to implement, this exercise was definitely worth
doing. I think there should be a more elegant way to construct the tree using
maybe a stack, but I couldn't find it.

All of this was part of a larger effort to search a string for a variety of
patterns. The solution is to compile the string into a suffix tree and then
search the suffix tree for each of the patterns.

I'm glad I didn't gloss over this exercise.
2020-11-19 00:35:23 +00:00
Griffin Smith
8d24a975f1 fix(tvix): Use copy constructor to add strings to protos
Passing a string directly to add_paths like this causes the proto class
to take ownership over the string, meaning when it is destructed it
will *explicitly* free the string. When the string's actual owner (the
derivation struct) then goes out of scope it'll get freed again, causing
a double-free. This fixes that to instead use the copy constructor to
assign to a pointer to a new path, and covers the whole to_proto method
with a rapidcheck test.

Fixes: b/64
Change-Id: I84235bed9104ff430a0acf686d4a96f1e2e9a897
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2106
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI
2020-11-19 00:29:42 +00:00
Griffin Smith
20e206a3f6 fix(tvix): Use mutable field for assigning proto fields
This was accidentally using the proto arena API to assign the derivation
field of a BuildDerivationRequest. We *thought* this was causing a
double free, but even with this change that's still happening. That
said, this change is probably still a good idea since it's using the
proto API as intended.

References: b/64
Change-Id: I950a4eafb214e9113639ea54d2dfd4659b7be931
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2104
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
2020-11-19 00:29:42 +00:00
glittershark
e1067b1497 revert(panettone): announce newly created issues using irccat
This reverts commit 2e2bdf9c6c.

Reason for revert: this is not working, and is resulting in newly created issues just showing a blank page (b/74)

Change-Id: I3f06afc52d6c5289269402fc75bb32ad9c376bf4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2082
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
2020-11-19 00:29:28 +00:00
multi
4331bc8da7 chore(users/multi): Update htop derivation for new upstream.
- htop has moved upstreams, which has been producing new releases, so
  update the derivation to pull from the new repository on GitHub.

- All of the patches I have locally have been merged upstream, so drop
  them from the depot.

- Pull from a reasonably recent git commit instead of from a numbered
  release, as the ZFS ARC stats and CPU meter columnation patches
  haven't made it into a release yet.

Change-Id: I66ad4c035df07709abf4f75a9d4e1486920091d0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2105
Reviewed-by: multi <depot@in-addr.xyz>
Tested-by: BuildkiteCI
2020-11-18 00:29:58 +00:00
William Carroll
c0268ed31a Refactor random-choice
Prefer initializing `result` to an empty array of size `m`, which makes the
algorithm a bit more elegant.
2020-11-17 23:54:54 +00:00
Vincent Ambo
73c862279a feat(ops/pipelines): Check in the static pipeline
This file represents the static pipeline which is configured in the
Buildkite web UI. Updates to this file should be applied in the admin
interface.

These steps are responsible for launching the dynamic pipeline
evaluation, or falling back to the fallback pipeline if evaluation fails.

Change-Id: I6d7dd623cde65e8c69faea729f737c9bba00c2fb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2103
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
2020-11-17 22:33:11 +00:00
Vincent Ambo
1857334d37 feat(ops/pipelines): Add a fallback Buildkite configuration
This adds a simple fallback Buildkite pipeline configuration which
always fails the pipeline, but correctly reports back the failure
status.

Note that this also requires changes in the Buildkite configuration
that is not in version-control.

Relates to b/66.

Change-Id: I6802a6f76448c3893798a06d514e6ccba0f50dd2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2102
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
2020-11-17 22:33:11 +00:00
William Carroll
751b5327a9 Solve algorithms dealing with randomness
Tonight I learned that random sample where each element in the sampling corpus
has an equal likelihood of being chosen is a brand of algorithms known as
"reservoir sampling".

- Implement random.shuffle(..)
- Implement random.choice(..)

Surprisingly, candidates are expected to encounter problems like this during
interviews.
2020-11-17 22:28:24 +00:00
Vincent Ambo
77097f8056 feat(ops/panettone): Add configuration for irccat
Adds configuration options for the (inconsistently named) environment
variables that configure irccat integration with Panettone.

The defaults match the irccat setup on whitby.

Change-Id: I6857512a2e3f29f16777493eb981cc69ce3c045f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2080
Tested-by: BuildkiteCI
Reviewed-by: kanepyork <rikingcoding@gmail.com>
2020-11-17 22:00:52 +00:00
William Carroll
572fb0fe5f Solve "nearby words" function
Given an input like "gello" suggest an correction like "hello".

This is a proof-of-concept problem for writing a simplistic auto-correction
algorithm for a mobile device.
2020-11-16 17:17:28 +00:00
William Carroll
6989c3a91a Implement the Rabin Karp string matching algorithm
This algorithm is pretty interesting because it runs in linear time with respect
to the length of the `corpus` string. It does this by using a sliding window
hash. This hash -- because it's a sliding window -- runs in constant time for
each iteration; we're only adding and subtracting one character each time and
not re-hashing the whole "window".

When our hashes match, only then do we compare the "window" to the
`pattern`. String comparisons are linear because they compare each character to
each character one at a time. But because we only compare strings when are
hashes match (a check which runs in constant time), this spares us the
performance hit.
2020-11-16 17:14:08 +00:00
William Carroll
a2fa88f561 Prefer mutative variant of delete for HashTable
Instead of calling `filter(..)`.
2020-11-16 17:13:39 +00:00
William Carroll
a457a81bbb Add another solution to the "move zeroes to end" problem
Support the optimally performance solution of which I'm aware.
2020-11-16 17:13:03 +00:00
William Carroll
ff08b723db Solve "find pairs for sum"
I have encountered this problem 3x in the wild thus far:
  1. www.InterviewCake.com
  2. Cracking the Coding Interview
  3. www.Pramp.com
2020-11-16 17:12:05 +00:00
William Carroll
92ab94943e Start working on the "Hard" problems
Firstly, implement a function that adds two arguments together... without using
the `+` operator. I need to drill this problem. Thankfully I took a Coursera
course that taught me how to make a half-adder and a full-adder, but the
recommended solution for this is a bit more difficult.
2020-11-16 17:10:57 +00:00
Griffin Smith
b1f2c2f48e feat(glittershark): Add resume + deploy it to gws.fyi
Change-Id: If9cf64c97621313af86074752d0959506059888a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2079
Reviewed-by: glittershark <grfn@gws.fyi>
Tested-by: BuildkiteCI
2020-11-16 16:10:43 +00:00
Griffin Smith
bdc5d0cfa0 feat(gs/emacs): Add some config for vterm
for some reason installing it directly via nix doesn't work atm, so I
have this hack here

Change-Id: I45093633c35e756988078eb136c6e7bc3c532eea
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2078
Reviewed-by: glittershark <grfn@gws.fyi>
Tested-by: BuildkiteCI
2020-11-16 16:10:43 +00:00
William Carroll
30f4d6f4a4 Implement a simple hash function and hash table
I was always curious how hashing functions were implemented, so I read about the
"polynomial rolling hash function", and I decided implementing it would be a
good exercise. After writing that, writing a hash table was simple.
2020-11-16 00:35:01 +00:00
William Carroll
363519273a Find the intersection (if any) between two linked lists
As with most linked list questions, this one involves an arcane trick from the
neck-bearded playbook.
2020-11-15 17:42:44 +00:00
William Carroll
c8330adfcb Solve "Move Zeroes to End"
Write a function to modify an array of integers in-place such that all of the
zeroes in the array are at the end, and the order of the other integers is not
changed.
2020-11-15 13:51:46 +00:00
William Carroll
09cd819a70 Include re-roll strategy for rand7
After seeing the solution that my book advocated, I implemented it using
recursion.
2020-11-14 17:36:04 +00:00
William Carroll
5820f6f459 Solve rand7
Write a random number generator for [0,7) using only a random number generator
for [0,5). Ensure the results are uniformly distributed.
2020-11-14 17:26:00 +00:00
William Carroll
a0e9e2b310 Solve unsorted-substring a second time
This solution operates in O(n) time instead of O(n*log(n)) time, which
surprisingly isn't *that* big of a difference...

Consider a size of n of 10M...
  1) ~10s
  2) ~0.5s

So, yes, the O(n*log(n)) will take 100x longer to complete, but for an enormous
input size of 10M elements, it can still complete in under a minute. The
difference between that and the second, faster, algorithm, is just 9s.
2020-11-14 15:28:23 +00:00
William Carroll
48fde5f278 Solve unsorted-substring
Write a function that returns the indices demarcating a substring, which if
sorted, would make the entire array sorted.
2020-11-14 15:08:25 +00:00
William Carroll
47c5c6ac05 Partially implement a Heap
Defining the insert (or "siftup") function described in the "Programming Pearls"
book.
2020-11-14 14:08:58 +00:00
William Carroll
c841527f61 Write encoded XML parser and pretty-printer
Write a function that reads a string of compressed XML and outputs the
decompressed version.

Note to self: Now that I'm growing more comfortable writing parsers, I'd like to
become equally comfortable writing pretty-printers.
2020-11-14 14:00:00 +00:00
William Carroll
bfd2180e6b Solve tic-tac-toe checker
Write a function that verifies whether or not a tic-tac-toe board is valid.
2020-11-13 17:45:07 +00:00
William Carroll
1b3f1b99f5 Solve box-stacking problem
Write a function to compute the highest stack of boxes that can be created from
a list of boxes.
2020-11-13 16:57:47 +00:00
William Carroll
7672049e1c Solve N queens
After a five year hiatus, I decided to attempt to solve the famous N queens
problem again. This time, instead of modeling the chess board using a
`[[Bool]]`, I'm using `[Integer]` where the `Integer` indicates which column has
a queen. This is a bit lighter in RAM.
2020-11-13 16:56:02 +00:00
William Carroll
14f6169fcf Document subset of BNF for regex engine
Adding some documentation for my future self.
2020-11-13 16:55:39 +00:00
William Carroll
aa66d9b83d Add coding exercises for Facebook interviews
Add attempts at solving coding problems to Briefcase.
2020-11-12 14:37:29 +00:00
William Carroll
d2d772e43e Sort Emacs deps
Group Emacs dependencies like ivy together.
2020-11-12 11:20:27 +00:00
William Carroll
6d26f5b987 Mark additional movies as watched
Making progress...
2020-11-12 11:19:59 +00:00
William Carroll
69b6bda01b Style habit screen to accommodate footer
Add spacing to the bottom to make space for the footer.
2020-11-12 11:19:30 +00:00
eta
2e2bdf9c6c feat(panettone): announce newly created issues using irccat
- The new PANETTONE.IRC package contains the SEND-IRC-NOTIFICATION function,
  which opens a new TCP socket to irccat (if it's running and configured) in
  order to announce the creation of new issues.
- The IRCCATHOST and IRCCATPORT environment variables must be set for this to
  work.
- Additionally, the ISSUECHANNEL environment variable may be used to direct
  announcements at a given channel (otherwise it'll just use the first one).

Change-Id: I429a66f24d0f80ed10db173d6af7105fb1d3d023
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2077
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
2020-11-08 19:02:46 +00:00
Vincent Ambo
1442c5c8ac feat(whitby): Enable irccat module
Enables irccat, running as 'tvlbot' on ##tvl and ##tvl-dev and listening on TCP 4722.

Change-Id: Ia1eb533d0aacb0c15d6b3fa1cfd854ffbce27d23
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2075
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
Reviewed-by: lukegb <lukegb@tvl.fyi>
2020-11-08 18:38:08 +00:00
Vincent Ambo
cbfcf14301 feat(ops/irccat): Add a NixOS module for launching irccat
This module configures irccat by creating a JSON configuration file
from a user-supplied Nix struct (this is not checked for correctness),
and merging it recursively with secrets from
`/etc/secrets/irccat.json` at service launch time.

This way we get the ability to configure (most) options declaratively
via Nix, while providing the secrets outside of Nix.

Side note: We need to figure out a secrets distribution mechanism.

Tested: Wrote a dummy config in whitby/default.nix locally and checked
that this builds, but I have not actually run the service yet. I
expect that some minor tweaks will end up being necessary.

Change-Id: I02a2e8dc40a7f8417fd77afcf8a12ac3df117988
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2074
Tested-by: BuildkiteCI
Reviewed-by: lukegb <lukegb@tvl.fyi>
Reviewed-by: glittershark <grfn@gws.fyi>
2020-11-08 18:38:08 +00:00
Vincent Ambo
8a6d00aceb feat(3p/irccat): init at '06a985y4'
This is to be used for forwarding messages to our IRC channels.

Change-Id: I6362c6f50a22f504588a7161d41a170f4e7a6edc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2073
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
Reviewed-by: lukegb <lukegb@tvl.fyi>
2020-11-08 18:38:08 +00:00
Vincent Ambo
31939acd6c fix(buildLisp): Override LANG in sbclWith for misconfigured machines
Machines on which LANG is misconfigured have trouble with SBCL loading
files that contain characters in certain encodings. This overrides
whichever local LANG (if any) is set.

Change-Id: Ic4341a01c4393e7f697de6cecc58dea4f2d85987
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2076
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
2020-11-08 18:35:28 +00:00
Vincent Ambo
1d71c29919 chore(3p/exwm): Update derivation to build local sources
... this should also update my system EXWM.

Change-Id: Idfbbda67613ac678dc2d5f82533e1c6176ab4a28
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2072
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>
2020-11-08 01:26:53 +00:00
Vincent Ambo
6104f6514f chore(3p/emacs/exwm): Import from commit '0368127976bda29d35eed788edfe74644ecd3845'
Imported from 0368127976

git-subtree-dir: third_party/emacs/exwm
git-subtree-mainline: e84f9ef0ad
git-subtree-split: 0368127976
Change-Id: Id3af5610254180f42947d71265aad89def7c6a3d
2020-11-08 01:01:28 +01:00
Vincent Ambo
e84f9ef0ad fix(whitby): Use new IRC bouncer location for clbot
... I found this location in the logs, because the certs are now valid
for this, but I'm not actually sure if it's right.

Change-Id: I5ac88073e3bf6a95fead4c1d34515622c4416c6a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2070
Tested-by: BuildkiteCI
Reviewed-by: lukegb <lukegb@tvl.fyi>
2020-11-05 14:22:01 +00:00
Griffin Smith
e39b7e002c feat(ops/nixos/paroxysm): Set Restart = "always"
Sometimes (like today) paroxysm crashes. We'd like it to restart if that
happens.

Change-Id: I98841096bcd6605c4279744ae5c65a9c92092a21
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2069
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
2020-11-05 13:30:42 +00:00
Griffin Smith
b8c50979dd feat(gs/emacs): Disable truncate-lines in org mode
Change-Id: Ie1a539d894ae6223196f9e5b912317a00716ba72
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2067
Reviewed-by: glittershark <grfn@gws.fyi>
Tested-by: BuildkiteCI
2020-11-04 15:29:34 +00:00
Vincent Ambo
ac5ba13dce fix(tazjin/emacs): Do not assume '.txt' files are Markdown
Change-Id: I5cab039938e415facf81492e7e3775672ee45db9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2068
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI
2020-11-04 11:34:06 +00:00