clarketm

function getClockAngle(hours, minutes, isPortionWithTwelve) { // using 12-hour OR 24-hour clock notation
  hours = hours % 12;
  
  var hourMinPart = 0.5 * minutes, // 30 degrees per 60 minutes => 1/2 degree per 1 minute => 0.5 * minute
      hourHourPart = 30 * hours, // 30 degrees per 1 hour => 30 * hour
      minAngle = 6 * minutes, // 360 degrees per 60 minutes => 6 degrees per 1 minute => 6 * minute
      totalAngle = Math.abs(hourMinPart + hourHourPart - minAngle); // absolute difference

  return isPortionWithTwelve ? 360 - totalAngle : totalAngle; // subtract the total angle from 360 to get the portion w/ 12
}

clarketm

function findMin(array) {
  var min = array[0],
      count = 0;
  
  for (var i = 1; i < array.length; i++, count++) {
    if (array[i] < min) {
      min = array[i];
    }
  }
  console.log(count + " iterations");

clarketm

function isRansomNotePossible(newsArticle, ransomNote) {
  var availableChars = {};

  for (var r = 0; r < newsArticle.length; r++) {
    var asciiCode = newsArticle.charCodeAt(r);
    availableChars[asciiCode] = (availableChars[asciiCode] || 0) + 1
  }

  for (var r = 0; r < ransomNote.length; r++) {
    var asciiCode = ransomNote.charCodeAt(r);

clarketm

function isRansomNotePossible(newsArticle, ransomNote) {
  let availableChars = new Map();

  for (let r of newsArticle) {
    let asciiCode = newsArticle.charCodeAt(r);
    availableChars.set(asciiCode, (availableChars.get(asciiCode) || 0) + 1);
  }

  for (let r of ransomNote) {
    let asciiCode = ransomNote.charCodeAt(r);

clarketm

function findMinBinarySearch(array) {
  var left = 0, // index of first element
      right = array.length - 1, // index of last element.
      mid, // midpoint
      count = 0;

  while (array[left] > array[right]) {
    count++;
    mid = ~~((left + right) / 2); // math.floor of the midpoint
    if (array[mid] > array[right]) {

clarketm

function binarySearch(array, target) {

  var startIndex = 0,
      stopIndex = array.length - 1,
      middle,
      count = 0;

  while (startIndex < stopIndex) {
    count++;
    middle = ~~((stopIndex + startIndex) / 2);

clarketm

Studying for a Tech Interview Sucks, so Here's a Cheat Sheet to Help

This list is meant to be a both a quick guide and reference for further research into these topics. It's basically a summary of that comp sci course you never took or forgot about, so there's no way it can cover everything in depth. It also will be available as a gist on Github for everyone to edit and add to.

Data Structure Basics

###Array ####Definition:

• Stores data elements based on an sequential, most commonly 0 based, index.
• Based on tuples from set theory.

clarketm

function largestBinaryGap(num) {
  var bin = Math.abs(num).toString(2),
      finalMax = 0,
      currentMax;
  
  for (var i = 0; i < bin.length; i++) {
    currentMax = 0;
    while (bin[i] === "0") {
      ++currentMax && ++i;
    }

clarketm

function cyclicRotation(array, times) {
    var rotatedArray = array;
    
    while (times > 0) {
        var currentArray = rotatedArray.slice();
        
        for (var i = 0; i < currentArray.length; i++) {
            rotatedArray[(i+1)%currentArray.length] = currentArray[i];   
        }
        times--;

clarketm

grid = [['.', '.', '.', '.', '.', '.'],
        ['.', 'O', 'O', '.', '.', '.'],
        ['O', 'O', 'O', 'O', '.', '.'],
        ['O', 'O', 'O', 'O', 'O', '.'],
        ['.', 'O', 'O', 'O', 'O', 'O'],
        ['O', 'O', 'O', 'O', 'O', '.'],
        ['O', 'O', 'O', 'O', '.', '.'],
        ['.', 'O', 'O', '.', '.', '.'],
        ['.', '.', '.', '.', '.', '.']]