kennyxcao

SELECT  
    date_trunc('hour', dt) dt,
    ((array_agg(bid ORDER BY dt ASC))[1] +
     (array_agg(ask ORDER BY dt ASC))[1])/2 o,
    (MAX(bid) + MAX(ask))/2 h,
    (MIN(bid) + MIN(ask))/2 l,
    ((array_agg(bid ORDER BY dt DESC))[1] +
     (array_agg(ask ORDER BY dt DESC))[1])/2 c,
    SUM(bid_vol) bid_vol,
    SUM(ask_vol) ask_vol,

kennyxcao

// Make a message bus object for use in your client-side (in-browser) code.
// The name (label) of a message type should be called the topic, in your code. This is standard pub/sub nomenclature.
// The payload is optional.
// Subscribers must be notified in the exact order that they originally subscribed.

// inside component A...
// messageBus.subscribe('new_signup', function(payload) {
//   // do something with the payload
// });

kennyxcao

const vowelDoubler = function (array) {
  let count = 0;

  for (let i = 0; i < array.length; i++) {
    if (['a', 'e', 'i', 'o', 'u'].includes(array[i])) {
      count++;
    }
  }

  for (let i = array.length - 1, j = i + count; i >= 0; i--, j--) {

kennyxcao

/**
 * @param {number[]} nums
 * @return {number[]}
 */
var productExceptSelf = function(nums) {
    var output = nums.slice().fill(1);
    var temp = 1;
    
    for (var i = 0; i < nums.length; i++) {
        output[i] = temp;

kennyxcao

// O(n) space complexity solution
var kthSmallest = function(root, k) {
    var stack  = [];
    var count = 0;
    var node = root;
    
    while (node) {
        stack.push(node);
        node = node.left;
    }

kennyxcao

var Tree = function (val) {
  this.val = val;
  this.children = [];
};

const hasPathToSum = function(node, targetSum) {
  if (node.val === targetSum) {
    return true;
  }

kennyxcao

// Prompt: tackling floating-point imprecision with the CashAmount class

class CashAmount {
  constructor(double) {
    this.pennies = parseInt(double * 100, 10);
  }

  totalInPennies() {
    return this.pennies;
  }

kennyxcao

var http = require("http"),
    url = require("url"),
    path = require("path"),
    fs = require("fs")
    port = process.argv[2] || 8888;

http.createServer(function(request, response) {

  var uri = url.parse(request.url).pathname
    , filename = path.join(process.cwd(), uri);

kennyxcao

var BinaryTree = function (value) {
  this.value = value;
  this.left = null;
  this.right = null;
};

// Starting Level at root = 0
const findLargestLevel = function(node) {
  var queue = [[node, 0]];
  var levelSum = [];

kennyxcao

/**
 * @param {number} numRows
 * @return {number[][]}
 */

var generate = function(numRows) {
  var result = [];

  for (var i = 0; i < numRows; i++) {
    var row = [];