Questions and Answers: May 2017

Tuesday, May 16, 2017

FreeCodeCamp Wherefore Art Thou Sample Solution

FreeCodeCamp Everything Be True Sample Solution

Monday, May 15, 2017

FreeCodeCamp Binary Agents Sample Solution

function binaryAgent(str) {
var arr = str.split(" ");
var arr2 = [];
for(var i=0; i<arr.length; i++){
arr2.push(String.fromCharCode(parseInt(arr[i], 2)));
}
return arr2.join("");
}

binaryAgent("01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111");

FreeCodeCamp Steamroller Sample Solution

function steamrollArray(arr) {
// I'm a steamroller, baby
var flattened = arr.reduce(
function(a, b) {
return a.concat(Array.isArray(b) ? steamrollArray(b) : b);
},[]);
return flattened;
}

steamrollArray([[["a"]], [["b"]]]);

Saturday, May 13, 2017

FreeCodeCamp Drop It Sample Solution

FreeCodeCamp Finders Keepers Sample Solution

function findElement(arr, func) {
var filtered = arr.filter(func);
return filtered[0];
}

findElement([1, 3, 5, 8, 9, 10], function(num) { return num % 2 === 0; });

FreeCodeCamp Sum All Primes Sample Solution

FreeCodeCamp Sum All Odd Fibonacci Numbers Sample Solution

FreeCodeCamp Spinal Tap Case Sample Solution

function spinalCase(str) {
var str2 = str.replace(/([a-z](?=[A-Z]))/g,'$1 ');
var newStr = str2.replace(/\s|\x5F/g,"-");
return newStr.toLowerCase();
}

spinalCase("AllThe-small Things");

FreeCodeCamp Convert HTML Entities Sample Solution

FreeCodeCamp Sorted Union Sample Solution

FreeCodeCamp Missing Letters Sample Solution

FreeCodeCamp DNA Pairing Sample Solution

FreeCodeCamp Pig Latin Sample Solution

FreeCodeCamp Search and Replace Sample Solution

function myReplace(str, before, after) {
var test = '/'+ before +'/';
//return after;
if(before[0] == before[0].toUpperCase()){
var firstLetter = after.split('').splice(0,1);
var restOfTheWord = after.split('').splice(1,after.length).join('');
after = firstLetter[0].toUpperCase()+restOfTheWord;
}
var newstr = str.split(before).join(after);
return newstr;
}

myReplace("He is Sleeping on the couch", "Sleeping", "sitting");

FreeCodeCamp Roman Numeral Converter Sample Solution

FreeCodeCamp Diff Two Arrays Sample Solution

FreeCodeCamp Sum All Numbers In Range Sample Solution

function sumAll(arr) {
var sorted = arr.sort(function(a, b){return a-b});
var sum = 0;
for(var i=sorted[0]; i<=sorted[1]; i++){
sum += i;
}
return sum;
}

sumAll([1, 4]);

FreeCodeCamp Caesars Cipher Sample Solution

Friday, May 12, 2017

FreeCodeCamp Where Do I Belong Sample Solution

FreeCodeCamp Falsy Bouncer Sample Solution

function bouncer(arr) {
// Don't show a false ID to this bouncer.
var newArr = arr.filter(function(val){
return !!val;
});
return newArr;
}

bouncer([7, "ate", "", false, 9]);

FreeCodeCamp Mutations Sample Solution

FreeCodeCamp Slasher Flick Sample Solution

function slasher(arr, howMany) {
// it doesn't always pay to be first
for(var i=0; i<howMany; i++){
arr.shift();
}
return arr;
}

slasher([1, 2, 3], 2);

FreeCodeCamp Chunky Monkey Sample Solution

FreeCodeCamp Truncate A String Sample Solution

FreeCodeCamp Repeat A String Repeat A String Sample Solution

function repeatStringNumTimes(str, num) {
// repeat after me
var temp='';
if(num<=0){
return '';
} else {
for(var i=0; i<num; i++){
temp += str;
}
}
return temp;
}

repeatStringNumTimes("abc", 3);

FreeCodeCamp Confirm The Ending Sample Solution

FreeCodeCamp Return Largest Numbers In Arrays Sample Solution

FreeCodeCamp Title Case A Sentence Sample Solution

function titleCase(str) {
var arr = str.toLowerCase().split(' ');
var arr2 = [];
for(var i=0; i<arr.length; i++){
arr2.push(arr[i].substring(0,1).toUpperCase()+arr[i].substring(1,arr[i].length));
}
return arr2.join(' ');
}

titleCase("I'm a little tea pot");

FreeCodeCamp Find The Longest Word In A String Sample Solution

FreeCodeCamp Check For Palindromes Sample Solution

FreeCodeCamp Factorialize A Number Sample Solution

function factorialize(num) {
var prod = num;
if(num === 0){
return 1;
}
for(var i=num-1; i>0; i--){
prod *= i;
}
return prod;
}

factorialize(5);

FreeCodeCamp Reverse A String Sample Solution

function reverseString(str) {
return str.split('').reverse().join('');
}

reverseString("hello");

FreeCodeCamp Join Strings With Join Sample Solution

var joinMe = ["Split","me","into","an","array"];
var joinedString = '';

// Only change code below this line.

joinedString = joinMe.join(" ");

FreeCodeCamp Split Strings With Split Sample Solution

var string = "Split me into an array";
var array = [];

// Only change code below this line.

array = string.split(' ');

FreeCodeCamp Sort Arrays With Sort Sample Solution

var array = [1, 12, 21, 2];

// Only change code below this line.

array.sort(function(a, b) {
return b - a;
});

Thursday, May 11, 2017

FreeCodeCamp Filter Arrays With Filter Sample Solution

var oldArray = [1,2,3,4,5,6,7,8,9,10];

// Only change code below this line.

var newArray = oldArray.filter(function(val) {
return val < 6;
});

FreeCodeCamp Iterate Over Arrays With Map Sample Solution

var oldArray = [1,2,3,4,5];

// Only change code below this line.

var newArray = oldArray.map(function(val){
return val + 3;
});

FreeCodeCamp Generate Whole Random Numbers Within A Range Sample Solution

// Example
function ourRandomRange(ourMin, ourMax) {

return Math.floor(Math.random() * (ourMax - ourMin + 1)) + ourMin;
}

ourRandomRange(1, 9);

// Only change code below this line.

function randomRange(myMin, myMax) {

return Math.floor(Math.random() * (myMax - myMin + 1)) + myMin; // Change this line

}

// Change these values to test your function
var myRandom = randomRange(5, 15);

FreeCodeCamp Profile Lookup Sample Solution

//Setup
var contacts = [
{
"firstName": "Akira",
"lastName": "Laine",
"number": "0543236543",
"likes": ["Pizza", "Coding", "Brownie Points"]
},
{
"firstName": "Harry",
"lastName": "Potter",
"number": "0994372684",
"likes": ["Hogwarts", "Magic", "Hagrid"]
},
{
"firstName": "Sherlock",
"lastName": "Holmes",
"number": "0487345643",
"likes": ["Intriguing Cases", "Violin"]
},
{
"firstName": "Kristian",
"lastName": "Vos",
"number": "unknown",
"likes": ["Javascript", "Gaming", "Foxes"]
}
];

function lookUpProfile(firstName, prop){
// Only change code below this line
var returnValue = "";
for(var i=0; i < contacts.length; i++){
if(firstName === contacts[i].firstName && contacts[i].hasOwnProperty(prop) === true){
returnValue = contacts[i][prop];
break;
} else if(firstName === contacts[i].firstName && contacts[i].hasOwnProperty(prop) === false) {
returnValue = "No such property";
break;
} else {
returnValue = "No such contact";
}
}
return returnValue;
// Only change code above this line
}

// Change these values to test your function
//lookUpProfile("Akira", "likes");
lookUpProfile("Akira", "address");

FreeCodeCamp Iterate With Javascript While Loops Sample Solution

// Setup
var myArray = [];

// Only change code below this line.
var i = 0;
while(i < 5) {
myArray.push(i);
i++;
}

FreeCodeCamp Nesting For Loops Sample Solution

FreeCodeCamp Iterate Through An Array With A For Loop Sample Solution

// Example
var ourArr = [ 9, 10, 11, 12];
var ourTotal = 0;

for (var i = 0; i < ourArr.length; i++) {
ourTotal += ourArr[i];
}

// Setup
var myArr = [ 2, 3, 4, 5, 6];

// Only change code below this line
var total=0;
for (var i = 0; i < myArr.length; i++){
total += myArr[i];
}

FreeCodeCamp Iterate With Javascript For Loops Sample Solution

// Example
var ourArray = [];

for (var i = 0; i < 5; i++) {
ourArray.push(i);
}

// Setup
var myArray = [];

// Only change code below this line.
for (var i = 0; i < 5; i++) {
myArray.push(i+1);
}

FreeCodeCamp Accessing Nested Arrays Sample Solution

// Setup
var myPlants = [
{
type: "flowers",
list: [
"rose",
"tulip",
"dandelion"
]
},
{
type: "trees",
list: [
"fir",
"pine",
"birch"
]
}
];

// Only change code below this line

var secondTree = myPlants[1].list[1];

FreeCodeCamp Accessing Nested Objects Sample Solution

// Setup
var myStorage = {
"car": {
"inside": {
"glove box": "maps",
"passenger seat": "crumbs"
},
"outside": {
"trunk": "jack"
}
}
};

// Only change code below this line

var gloveBoxContents = myStorage.car.inside["glove box"];

FreeCodeCamp Manipulating Complex Objects Sample Solution

var myMusic = [
{
"artist": "Billy Joel",
"title": "Piano Man",
"release_year": 1973,
"formats": [
"CS",
"8T",
"LP" ],
"gold": true
}
// Add record here
];
myMusic.push({
"artist": "John Mayer",
"title": "Continuum Extended",
"release_year": 2017,
"formats": [
"CS",
"8T",
"LP" ]
});

FreeCodeCamp checkObj(checkProp) Sample Solution

// Setup
var myObj = {
gift: "pony",
pet: "kitten",
bed: "sleigh"
};

function checkObj(checkProp) {
// Your Code Here

if(myObj.hasOwnProperty(checkProp)){
return myObj[checkProp];
} else {
return "Not Found";
}
}

// Test your code by modifying these values
checkObj("gift");

FreeCodeCamp phoneticLookup(val) Sample Solution

function phoneticLookup(val) {
var result = "";

// Only change code below this line
var lookup = {
"alpha":"Adams",
"bravo":"Boston",
"charlie":"Chicago",
"delta":"Denver",
"echo":"Easy",
"foxtrot":"Frank"
};
result = lookup[val];
// Only change code above this line
return result;
}

FreeCodeCamp Counting Cards Sample Solution

FreeCodeCamp abTest(a,b) Sample Solution

function abTest(a, b) {
// Only change code below this line
if(a < 0 || b < 0){
return undefined;
}
// Only change code above this line

return Math.round(Math.pow(Math.sqrt(a) + Math.sqrt(b), 2));
}

FreeCodeCamp chainToSwitch(val) Sample Solution

function chainToSwitch(val) {
var answer = "";
// Only change code below this line
switch(val){
case "bob":
answer = "Marley";
break;
case 42:
answer = "The Answer";
break;
case 1:
answer = "There is no #1";
break;
case 99:
answer = "Missed me by this much!";
break;
case 7:
answer = "Ate Nine";
break;
}
// Only change code above this line
return answer;
}

FreeCodeCamp sequentialSizes(val) Sample Solution

function sequentialSizes(val) {
var answer = "";
// Only change code below this line
switch(val){
case 1:
case 2:
case 3:
answer = "Low";
break;
case 4:
case 5:
case 6:
answer = "Mid";
break;
case 7:
case 8:
case 9:
answer = "High";
break;
}
// Only change code above this line
return answer;
}

FreeCodeCamp switchOfStuff Sample Solution

function switchOfStuff(val) {
var answer = "";
// Only change code below this line
switch(val){
case "a":
answer = "apple";
break;
case "b":
answer = "bird";
break;
case "c":
answer = "cat";
break;
default:
answer = "stuff";
}
// Only change code above this line
return answer;
}

FreeCodeCamp First Switch Exercise

//sample solution
function caseInSwitch(val) {
var answer = "";
// Only change code below this line
switch(val){
case 1:
answer = "alpha";
break;
case 2:
answer = "beta";
break;
case 3:
answer = "gamma";
break;
case 4:
answer = "delta";
break;
}
// Only change code above this line
return answer;
}

FreeCodeCamp Golf Code

//sample solution
function golfScore(par, strokes) {
// Only change code below this line
if(strokes == 1){
return "Hole-in-one!";
} else if(strokes <= par - 2) {
return "Eagle";
} else if(strokes == par - 1) {
return "Birdie";
} else if(strokes == par) {
return "Par";
} else if(strokes == par + 1) {
return "Bogey";
} else if(strokes == par + 2) {
return "Double Bogey";
} else if(strokes >= par + 3) {
return "Go Home!";
}
// Only change code above this line
}

Tuesday, May 9, 2017

Codecademy Learn ReactJS: Part 1 Exercise 13 of 15

//sample solution to app.js

var React = require('react');
var ReactDOM = require('react-dom');

// Write code here:
var myList = (
<ul>
<li>
Superman
</li>
<li>
Batman
</li>
<li>
Flash
</li>
<li>
Aquaman
</li>
<li>
Wonderwoman
</li>
</ul>
);

ReactDOM.render(myList,document.getElementById('app'));

Codecademy Learn ReactJS: Part 1 Exercise 12 of 15

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<link rel="stylesheet" href="/styles.css">
<title>Learn ReactJS</title>
</head>

<body>
<span id="container"></span>
<script src="/app.compiled.js"></script>
</body>

</html>

//sample solution to app.js
var React = require('react');
var ReactDOM = require('react-dom');

// Write code here:
ReactDOM.render(<h1>Render me!</h1>, document.getElementById('container'));

Codecademy Learn ReactJS: Part 1 Exercise 11 of 15

//sample solution to app.js
var React = require('react');
var ReactDOM = require('react-dom');

// Write code here:
ReactDOM.render(<h1>Render me!</h1>,document.getElementById('app'));

Codecademy Learn ReactJS: Part 1 Exercise 10 of 15

var React = require('react');
var ReactDOM = require('react-dom');

ReactDOM.render(<h1>Hello world</h1>, document.getElementById('app'));

Codecademy Learn ReactJS: Part 1 Exercise 9 of 15

var blog = (
<div>
<img src="pics/192940u73.jpg" />
<h1>
Welcome to Dan's Blog!
</h1>
<article>
Wow I had the tastiest sandwich today. I <strong>literally</strong> almost freaked out.
</article>
</div>
);

Codecademy Learn ReactJS: Part 1 Exercise 8 of 15

var myDiv = (
<div>
<h1>
Hello world
</h1>
</div>
);

Codecademy Learn ReactJS: Part 1 Exercise 7 of 15

var p1 = <p id="large">foo</p>;
var p2 = <p id="small">bar</p>;

Codecademy Learn ReactJS: Part 1 Exercise 6 of 15

var myArticle = <article>An article</article>;

Codecademy Learn ReactJS: Part 1 Exercise 5 of 15

<p>Hello world</p>

Codecademy SQL: Analyzing Business Metrics Exercise 13 of 14

--first answer

select
date(g1.created_at) as dt,
g1.user_id,
g2.user_id
from gameplays as g1
join gameplays as g2 on
g1.user_id = g2.user_id
and date(g1.created_at) = date(datetime(g2.created_at, '-1 day'))
order by 1
limit 100;

--second answer

select
date(g1.created_at) as dt,
count(distinct g1.user_id) as total_users,
count(distinct g2.user_id) as retained_users
from gameplays as g1
left join gameplays as g2 on
g1.user_id = g2.user_id
and date(g1.created_at) = date(datetime(g2.created_at, '-1 day'))
group by 1
order by 1
limit 100;

--third answer

select
date(g1.created_at) as dt,
round(100 * count(distinct g2.user_id) /
count(distinct g1.user_id)) as retention
from gameplays as g1
left join gameplays as g2 on
g1.user_id = g2.user_id
and date(g1.created_at) = date(datetime(g2.created_at, '-1 day'))
group by 1
order by 1
limit 100;

Codecademy SQL: Analyzing Business Metrics Exercise 12 of 14

--first answer

select
date(created_at) as dt,
user_id
from gameplays as g1
order by dt
limit 100;

--second answer

select
date(g1.created_at) as dt,
g1.user_id
from gameplays as g1
join gameplays as g2 on
g1.user_id = g2.user_id
order by 1
limit 100;

Codecademy SQL: Analyzing Business Metrics Exercise 9 of 14

--first answer

with daily_revenue as (
select
date(created_at) as dt,
round(sum(price), 2) as rev
from purchases
where refunded_at is null
group by 1
),
daily_players as (
select
date(created_at) as dt,
count(distinct user_id) as players
from gameplays
group by 1
)
select * from daily_players order by dt;

--second answer

with daily_revenue as (
select
date(created_at) as dt,
round(sum(price), 2) as rev
from purchases
where refunded_at is null
group by 1
),
daily_players as (
select
date(created_at) as dt,
count(distinct user_id) as players
from gameplays
group by 1
)
select
daily_revenue.dt,
daily_revenue.rev / daily_players.players
from daily_revenue
join daily_players using (dt);

Codecademy SQL: Analyzing Business Metrics Exercise 8 of 14

with daily_revenue as (
select
date(created_at) as dt,
round(sum(price), 2) as rev
from purchases
where refunded_at is null
group by 1
)
select * from daily_revenue order by dt;

Codecademy SQL: Analyzing Business Metrics Exercise 6 of 14

select
date(created_at),
round(sum(price) / count(distinct user_id), 2) as arppu
from purchases
where refunded_at is null
group by 1
order by 1;

Codecademy SQL: Analyzing Business Metrics Exercise 5 of 14

select
date(created_at),
platform,
count(distinct user_id) as dau
from gameplays
group by 1, 2
order by 1, 2;

Codecademy SQL: Analyzing Business Metrics Exercise 4 of 14

select
date(created_at),
count(distinct user_id) as dau
from gameplays
group by 1
order by 1;

Codecademy SQL: Analyzing Business Metrics Exercise 3 of 14

select
date(created_at),
round(sum(price), 2) as daily_rev
from purchases
where refunded_at is not null
group by 1
order by 1;

Codecademy SQL: Analyzing Business Metrics Exercise 2 of 14

select
date(created_at),
round(sum(price), 2)
from purchases
group by 1
order by 1;

Codecademy SQL: Analyzing Business Metrics Exercise 1 of 14

--first answer

select *
from purchases
order by id
limit 10;

--second answer

select *
from gameplays
order by id
limit 10;

Friday, May 5, 2017

Codecademy SQL SpeedySpoon Exercise 11

select name, count(DISTINCT order_id)
from order_items
group by 1
order by 1;

-- number of people making the orders

select name, round(1.0 * count(DISTINCT order_id) /
count(DISTINCT delivered_to), 2) as reorder_rate
from order_items
join orders on
orders.id = order_items.order_id
group by 1
order by 2 desc;

Codecademy SQL SpeedySpoon Exercise 9

select *,
case name
when 'kale-smoothie' then 'smoothie'
when 'banana-smoothie' then 'smoothie'
when 'orange-juice' then 'drink'
when 'soda' then 'drink'
when 'blt' then 'sandwich'
when 'grilled-cheese' then 'sandwich'
when 'tikka-masala' then 'dinner'
when 'chicken-parm' then 'dinner'
else 'other'
end as category
from order_items
order by id
limit 100;

-- percentages

select
case name
when 'kale-smoothie' then 'smoothie'
when 'banana-smoothie' then 'smoothie'
when 'orange-juice' then 'drink'
when 'soda' then 'drink'
when 'blt' then 'sandwich'
when 'grilled-cheese' then 'sandwich'
when 'tikka-masala' then 'dinner'
when 'chicken-parm' then 'dinner'
else 'other'
end as category, round(1.0 * sum(amount_paid) /
(select sum(amount_paid) from order_items) * 100, 2) as pct
from order_items
group by 1
order by 2 desc;

Codecademy SQL SpeedySpoon Exercise 7

select name, round(sum(amount_paid) /
(select sum(amount_paid) from order_items) * 100.0, 2) as pct
from order_items
group by 1
order by 2 desc;

Codecademy SQL SpeedySpoon Exercise 6

select name, round(sum(amount_paid), 2)
from order_items
group by name
order by 2 desc;

Codecademy SQL SpeedySpoon Exercise 4

select date(ordered_at), round(sum(amount_paid), 2)
from orders
join order_items on
orders.id = order_items.order_id
group by 1
order by 1;

--for kale-smoothie

select date(ordered_at), round(sum(amount_paid), 2)
from orders
join order_items on
orders.id = order_items.order_id
where name = 'kale-smoothie'
group by 1
order by 1;

Codecademy SQL SpeedySpoon Exercise 3

select date(ordered_at), count(1)
from orders
group by 1
order by 1;

Codecademy SQL SpeedySpoon Exercise 2

select date(ordered_at)
from orders
order by 1
limit 100;

Codecademy SQL SpeedySpoon Exercise 1

select *
from orders
order by id
limit 100;

select *
from order_items
order by id
limit 100;

Codecademy SQL Replace enriched_flour with flour

SELECT REPLACE(ingredients,'enriched_',' ') as item_ingredients
FROM baked_goods;

Codecademy SQL Combine the first_name and last_name columns from the bakeries table

SELECT first_name || ' ' || last_name as full_name
FROM bakeries;

Codecademy SQL Find the greatest and least time value for cool down and cook time for each item in the table

--Greatest Time
SELECT id, MAX(cook_time, cool_down_time)
FROM baked_goods;

--Least Time
SELECT id, MIN(cook_time, cool_down_time)
FROM baked_goods;

Codecademy SQL Find the bakery's distance from the market rounded to two decimal places

SELECT ROUND(distance, 2) as distance_from_market FROM bakeries;

Codecademy SQL Create a query returning all the packaging times for the goods

SELECT DATETIME(delivery_time, '+5 hours', '20 minutes', '2 days') as package_time
FROM baked_goods;

Codecademy SQL Find the number of baked goods by date of delivery

SELECT DATE(delivery_time), count(*) as count_baked_goods
FROM baked_goods
GROUP BY DATE(delivery_time);

Codecademy Sample Solution for delivery_time

Using the datetime function, select the date and time of all deliveries in the baked_goods table using the column delivery_time.

SELECT DATETIME(delivery_time) FROM baked_goods;

Thursday, May 4, 2017

Codecademy Select ten rows from the bakeries table

SELECT * FROM bakeries LIMIT 10;