const luhnCheck = num => {
  let arr = (num + '')
    .split('')
    .reverse()
    .map(x => parseInt(x));
  let lastDigit = arr.splice(0, 1)[0];
  let sum = arr.reduce(
    (acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val *= 2) > 9 ? val - 9 : val)),
    0
  );
  sum += lastDigit;
  return sum % 10 === 0;
};

luhnCheck('4485275742308327'); // true
luhnCheck(6011329933655299); //  true
luhnCheck(123456789); // false

// Get the text that the user has selected
const getSelectedText = () => window.getSelection().toString();
getSelectedText();

//JavaScript program to swap two variables

//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');

// XOR operator
a = a ^ b
b = a ^ b
a = a ^ b

console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);

var invertTree = function(root) {
    const reverseNode = node => {
        if (node == null) {
            return null
        }
        reverseNode(node.left);
        reverseNode(node.right);
        let holdLeft = node.left;
        node.left = node.right;
        node.right = holdLeft;
        return node;
    }

    return reverseNode(root);
};

questions = Array.from(document.querySelectorAll(".multiple-choice-question"));
async function hackRadio(question){
	if(question.querySelector(".question-chevron").getAttribute("aria-label") == "Question completed") return;
	let answerChoices = question.querySelectorAll(".zb-radio-button");
	async function guess(answerChoice){
		answerChoice.querySelector("label").click();
	}
	let pause = 0;
	for(let answerChoice of answerChoices){
		setTimeout(()=>{guess(answerChoice)},pause);	//No need to check given that it will record the correct answer anyways.
		pause += 1000;
	}
}
for(let question of questions){
	hackRadio(question);
}
questions = Array.from(document.querySelectorAll(".short-answer-question"));
async function hackShortAnswer(question){
	if(question.querySelector(".question-chevron").getAttribute("aria-label") == "Question completed") return;
	question.querySelector("textarea").value = question.querySelector(".forfeit-answer").textContent;
	//question.querySelector(".check-button").click(); They are smart bastards
}
for(let question of questions){
	const showAnswerButton = question.querySelector(".show-answer-button");
	showAnswerButton.click();
	showAnswerButton.click();
	hackShortAnswer(question);
}

const getSearchTerm = delimiter => {
	let searchTerm = "";

	for (let i = 1; i < commands.length - 1; i++)
	searchTerm = searchTerm + commands[i] + delimiter;

	searchTerm += commands[commands.length - 1];

	return searchTerm;
	};