tlehman

ITEMS = [6,2,2,4].map { |q| {quantity: q} }
KNAPSACKS = [10,4,4].map { |c| {capacity: c} }
N = ITEMS.length
M = KNAPSACKS.length
A = Array.new(N*M, 0)

# [0 1 1 1         [3
#  1 0 0 0  ---->   1
#  0 1 0 1]         2]
def sum_rows(x, w)

tlehman

Pub/Sub pattern with PostgreSQL's LISTEN/NOTIFY command

This is a simple chat-like program using pub-sub pattern, backed by PostgreSQL's LISTEN/NOTIFY command.

Publish

publish message to foo channel from user nickname.

$ python pub.py foo nickname
PUBLISH to channel #foo

tlehman

//: Playground - noun: a place where people can play

import UIKit

// generic function using pass by reference
func swap<T>(inout a: T, inout b: T) {
    let tempA: T = a
    a = b
    b = tempA
}

tlehman

# Python boolean fail
# Or how to redefine True and False and win any argument on the internet!
# Love, @tlehman
from unittest import TestCase

class BoolFail(TestCase):
    def test_false(self):
	True = False
	assert True == False

tlehman

puts UDPSocket.open { |s| s.connect('www.example.com', 1); s.addr.last }

tlehman

Normalization in data modeling

Say you have a service where users can add products they like to a wish list, representing this with JSON, you might expect something like this:

[
  {
    "user_id": 3,
    "email": "foo@example.com",
 "wishlist": [

tlehman

$ curl -s https://rubygems.org/gems/faraday | ruby -rnokogiri -e "puts Nokogiri::HTML(STDIN.read).css('.gem__desc p').children.first"
HTTP/REST API client library.

$ curl -s https://rubygems.org/gems/nokogiri | ruby -rnokogiri -e "puts Nokogiri::HTML(STDIN.read).css('.gem__desc p').children.first"
Nokogiri (鋸) is an HTML, XML, SAX, and Reader parser.  Among Nokogiri's
many features is the ability to search documents via XPath or CSS3 selectors.

XML is like violence - if it doesn’t solve your problems, you are not using
enough of it.

tlehman

# Balanced paren strings have the property that each opening ( has a closing ).
# This proceeds by scanning left to right, using a stack to keep track of open 
# parens.
def balanced?(string)
  characters = string.split(//)
  stack = []
  characters.each do |c|
    stack.push(c) if c == "(" 

    return false if stack.empty? and c == ")"

tlehman

Keybase proof

I hereby claim:

• I am tlehman on github.
• I am tlehman (https://keybase.io/tlehman) on keybase.
• I have a public key whose fingerprint is 702A 8535 CE1D D733 D885 D431 FD0E 4D25 7D77 5AEB

To claim this, I am signing this object:

tlehman

// clever trick from http://stackoverflow.com/a/8618383/46871
var arraysEqual = function(a,b) { return !!a && !!b && !(a<b || b<a); }