jboner

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

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

tsiege

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!






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subfuzion

There are certain files created by particular editors, IDEs, operating systems, etc., that do not belong in a repository. But adding system-specific files to the repo's .gitignore is considered a poor practice. This file should only exclude files and directories that are a part of the package that should not be versioned (such as the node_modules directory) as well as files that are generated (and regenerated) as artifacts of a build process.

All other files should be in your own global gitignore file:

• Create a file called .gitignore in your home directory and add any filepath patterns you want to ignore.
• Tell git where your global gitignore file is.

Note: The specific name and path you choose aren't important as long as you configure git to find it, as shown below. You could substitute .config/git/ignore for .gitignore in your home directory, if you prefer.

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

amadamala

public class HashTable {
    private static int INITIAL_SIZE = 16;
    private HashEntry[] entries = new HashEntry[INITIAL_SIZE];
    public void put(String key, String value) {
        int hash = getHash(key);
        final HashEntry hashEntry = new HashEntry(key, value);
        if(entries[hash] == null) {
            entries[hash] = hashEntry;
        }
        // If there is already an entry at current hash

leonardofed

A curated list of AWS resources to prepare for the AWS Certifications

A curated list of awesome AWS resources you need to prepare for the all 5 AWS Certifications. This gist will include: open source repos, blogs & blogposts, ebooks, PDF, whitepapers, video courses, free lecture, slides, sample test and many other resources.

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sharmaeklavya2

Competitive Programming Syllabus

Geometry

• Graham Scan algorithm for Convex Hull O(n * log(n))
• Online construction of 3-D convex hull in O(n^2)
• Bentley Ottmann algorithm to list all intersection points of n line segments in O((n + I) * logn)
  • Suggested Reading - http://softsurfer.com/Archive/algorithm_0108/algorithm_0108.htm
• Rotating Calipers Technique
  • Suggested Reading - http://cgm.cs.mcgill.ca/~orm/rotcal.html

• Problems - Refer the article for a list of problems which can be solved using Rotating Calipers technique.

jayant91089

121 Best Time to Buy and Sell Stock

Say you have an array for which the ith element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Example 1: Input: [7, 1, 5, 3, 6, 4] Output: 5

xirixiz

SSH keypair setup for GitHub (or GitHub/GitLab/BitBucket, etc, etc)

Create a repo.

Make sure there is at least one file in it (even just the README.md)

Generate a SSH key pair (private/public):

ssh-keygen -t rsa -C "your_email@example.com"