vasuadari

DSA Cheat Sheet for Meta Interview Preparation

Arrays & Strings

• Two Pointers:
  Use when working with sorted arrays or to solve problems like pair-sum and partitioning (e.g., “left and right pointers meet in the middle”).
• Sliding Window:
  Ideal for subarray problems—expand or contract the window to meet the required sum or length conditions.
• Prefix Sums:
  Precompute cumulative sums to answer range queries in O(1) time.
• In-place Reversal:

vasuadari

Here’s a quick cheat sheet for common data types and their storage sizes across popular relational databases (like MySQL, PostgreSQL, and SQL Server). Keep in mind that the sizes listed are typical, but some nuances or variations might apply based on specific DBMS configurations.

Numeric Data Types

Data Type	Description	Storage Size (in bytes)
TINYINT	Integer between -128 and 127 (signed)	1
SMALLINT	Integer between -32,768 and 32,767 (signed)	2
MEDIUMINT	Integer between -8,388,608 and 8,388,607	3
INT/INTEGER	Integer between -2,147,483,648 and 2,147,483,647	4
BIGINT	Large integer between -9 quintillion to +9 quintillion	8

vasuadari

Here’s how the SOLID principles can be implemented using Ruby:

1. Single Responsibility Principle (SRP):

• Violation:

  class User
    def initialize(name, email)
      @name = name
      @mail = email
    end

vasuadari

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

vasuadari

// src: https://www.javatpoint.com/template-pattern

public interface Base {
  boolean supports(EventModel event);
  
  void apply(EventModel event);
}

// All different types of classes can implement this Base.

vasuadari

Lets assume we're gonna cook for 3 people.

Things to buy

• 500 to 600 grams of chicken which is mediumly cut
• India gate basmati rice
• 250 ml of Curd(Should be thick so go for milky mist cup or some other brand)
• Garam masala
• Biriyani masala
• Red chilli powder

vasuadari

defmodule Tap do
  defmacro tap(tapped_value, do: yield) do
    quote do
      var!(t) = unquote(tapped_value)
      unquote(yield)
      var!(t)
    end
  end

  defmacro tap(tapped_value, :return, do: yield) do

vasuadari

defmodule DefaultModule do
  @callback hello(any()) :: any()

  defmacro __using__(_opts) do
    quote do
      @behaviour DefaultModule

      def hello(:a) do
        :a
      end

vasuadari

MySQL

Dump a query result to a csv file

mysql -h [HOST] -P [PORT] -u [USER] DB_NAME -e '[QUERY]' -p > [FILE_NAME].csv

Networking

vasuadari

# Copy of https://gist.github.com/antonio/4586456
# With a modification to collect all the branch names so we can make one git request
# Set DRY_RUN=1 to get an echo of the command

# Format that works with `git log --since`, e.g. 2018-01-01
date=$1

branches=

for branch in $(git branch -r | sed 's/^\s*//' | sed 's/^remotes\///' | grep -v 'master$'); do