drbr’s gists

drbr / sortArguments.c

Last active December 22, 2016 00:29

C program to sort items given as input arguments

	#include "stdlib.h"
	#include "stdio.h"
	#include "string.h"

	/*
	* Returns a string containing each argument separated by a newline.
	*/
	char* parse_args(int argc, char** argv) {
	int char_count = 0;
	for (int i = 1; i < argc; i++) {

drbr / extract_pages.sh

Last active April 28, 2016 01:12

A shell script that uses pdftk to break a PDF file into smaller files, each with an equal number of pages

	#!/bin/zsh

	if (($# != 2)); then
	echo
	echo "This script breaks the given PDF file into a set of PDf files,"
	echo "each with block_size pages."
	echo
	echo "Usage:"
	echo " extract_pages.sh filename block_size"
	echo

drbr / infinite_product_to_pi.py

Last active August 9, 2016 06:47

Python script that computes successive iterations of an infinite product that converges to π

	# Computes the value of pi by iteratively evaluating the infinite product:
	# 4 * (8/9) * (24/25) * (48/49) * (80/81) * (120/121) * (168/169) * ...
	# Each line of output shows the last denominator considered so far, and
	# the value of the finite product at that point.
	#
	# As featured by Matt Parker: https://www.youtube.com/watch?v=8pj8_zjelDo

	from decimal import *

	def converge():

drbr / repeat.zsh

Created October 15, 2016 01:53

When a command is specified as arguments, runs the command multiple times, printing out the number of the iteration, and waits for the user to press Enter between each run.

	#!/bin/zsh
	i=0
	while { true }; do
	echo $((++i)):
	$@
	read
	done

drbr / treeTraversal.js

Created December 20, 2016 06:46

A simple algorithm for traversing a binary search tree in-order without using recursion.

	function traverseTreeInOrder(tree) {

	// In the real world, we'd need a more robust solution of storing
	// and looking up object IDs. But JavaScript doesn't make that easy.
	const visitedNodes = {};

	const stack = [ tree ];
	while (stack.length > 0) {
	let node = stack.pop();
	if (!node) {

drbr / shuffleList.c

Created November 29, 2017 07:15

Sometimes I write things in C so I remember how.

	#include <stdio.h>

	#define ARR_SIZE 9

	void swap(int* a, int* b) {
	if (a == b) {
	return;
	}

	a = a ^ *b;

drbr / isPrime.js

Created September 1, 2018 17:26

Given a positive integer given as a command line argument, determines if that number is prime.

	#!/usr/bin/env node

	const process = require('process');
	const num = parseInt(process.argv[2], 10);

	const CompositeRegex = /^(..+)\1+$/;

	function isPrime(num) {
	const str = new Array(num + 1).join(' ');
	return !CompositeRegex.test(str);

drbr / XStateViz.tsx

Created November 26, 2020 07:26

XState Visualizer (XState Inspector) as a React component with a standalone state machine

	import { useEffect, useState } from 'react';
	import { StateMachine } from 'xstate';
	import { useMachine } from '@xstate/react';
	import { inspect } from '@xstate/inspect';

	let iFrameElement: HTMLIFrameElement \| null = null;

	function createIFrame() {
	if (!iFrameElement) {
	const iframe = document.createElement('iframe');

drbr / KeyOn.ts

Last active December 16, 2020 01:39

React HOC to render a wrapped component with a given key

	/**
	* Higher Order Component that renders the wrapped component with the given key (derived from its
	* props), which allows us to easily "reset" a component if certain props change.
	* @param component
	* @param getKey
	*/
	export function KeyOn<P>(component: React.ComponentType<P>, getKey: (props: P) => string) {
	const displayName = `KeyOn(${component.displayName})`;
	const hoc = (props: P) => {
	const key = getKey(props);

drbr / useAsyncFetch.ts

Last active December 19, 2020 03:35

Hook to fetch async data, a cheap knockoff of react-query

	import * as React from 'react';

	export type AsyncFetchState<T, E = unknown> = {
	data: T \| null;
	loading: boolean;
	error: E \| undefined;
	};

	/**
	* This hook performs an async operation and stores its result in component state. It protects

Andrew Brandon drbr