q3e

Variables

const shade = 100;
type Shade = 100;

Functions

q3e

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?

q3e

function checkCashRegister(price, cash, cid) {
var change = cash - price, // The change due
    count = 0,
    denomArr = [0.01, 0.05, 0.1, 0.25, 1, 5, 10, 20, 100],
    denominations = 9, // Number of denominations is a constant, check denomArr.length below
    changeArr = [],
    // Cash Drawer variables:
    bestFactor = 0,
    bestDenom = 0,
    indexBestDenom = 0,

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//This operation runs for 0.79ms - twice as previous version. PASSES for ALL array inputs.
//input expected is:
    /* 3 ≤ sequence.length ≤ 5 · 10^4,
     *1 ≤ sequence[i] ≤ 1000
    */
// NB revision, used Array.prototype.reduce()
      function arrayMode(sequence) {
        var countArr = [],
            mod, count =0,
            _seq = sequence.slice(0),

q3e

//doesnt work yet
function isMAC48Address(inputString) {
        MAC  = inputString.split('-');
        var regExChar = new RegExp('^[a-zA-Z]'),
          regExNum = new RegExp('^[a-zA-Z]'),
          bool = false;
        console.log(MAC);
        if(MAC.length === 6){
        MAC.forEach(function(elem,idx,array){
            if(elem.length === 2){

q3e

function sym(args) {
  var argsArr = Array.from(arguments),
      arrLen = argsArr.length,
      x = [],
      //function to get symmetric Difference of 2 arrays
      symDiffOfTwo = function(arr1, arr2){
        //set default value of arr2 - es5
        arr2 = arr2 || [] ;
        arr1 = arr1 || [] ;
        var diff = arr2.slice(0),

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//works but needs improvements
function telephoneCheck(str) {
  var isUSPhoneNum = false,
      strArr = str.split(''),
      numOfBracs = strArr.join('').split('(').length -1,
      numsOnly = str.replace(/-|\s|[{()}]|[^0-9\-]/g,""),
      numsLen = numsOnly.length,
      firstNum = numsOnly.charAt(0),
      firstParenth = str.indexOf('('),
      secondParenth = str.indexOf(')'),

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function addTogether() {
  var args1 = arguments[0],//1st arg to the function
      args2 = arguments[1];//2nd arg to the function
  if(typeof args1 === 'number'){
    //both arguments are numbers
    if(typeof args2 === 'number'){
      return args1 + args2;
    }
    //one argument missing
    if(args2 === undefined){

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function truthCheck(collection, pre) {
  var x = {};
  var count = 0;
  var len = collection.length;
  for(var i=0;i<len;i++){
    var prop = collection[i][pre];
    /*a JS val like prop evals to true if its not a null,undefined,NaN,(""),0,false*/
    if(collection[i].hasOwnProperty(pre)&& prop){
      count++;
    }

q3e

function binaryAgent(str) {
  var arr = [];
  //seperate array elems between spaces
  str = str.split(' ').map(Number)
  //convert elems from binary to decimals
    .map( function( num ){ return (parseInt(num, 2));});
  //convert binary string into English!
  str.forEach(function(code){
    arr.push(String.fromCharCode(code));
  });