Recursion Quiz

To pass the quiz, you must correctly answer at least 9 of the 10 questions below. # --quizzes-- ## --quiz-- ### --question-- #### --text-- What is recursion in programming? #### --distractors-- A method of sorting arrays. --- A loop that never ends. --- A function that returns `undefined`. #### --answer-- A process in which a function calls itself. ### --question-- #### --text-- Which of the following is an example of recursion? #### --distractors-- ```js function factorial(n) { let result = 1; while (n > 0) { result = result * n; n--; } return result; } ``` --- ```js function factorial(n) { const arr = Array(n).fill().map((_, i) => i + 1); return arr.reduce((acc, curr) => acc * curr, 1); } ``` --- ```js function factorial(n) { let result = 1; for (let i = n; i > 0; i--) { result *= i; } return result; } ``` #### --answer-- ```js function factorial(n) { if (n === 0 || n === 1) { return 1; } return n * factorial(n - 1); } ``` ### --question-- #### --text-- What will the following function return? ```js function sum(n) { if (n === 0) return 0; return n + sum(n - 1); } sum(3); ``` #### --distractors-- 3 --- 0 --- 1 #### --answer-- 6 ### --question-- #### --text-- How many times will the `mystery` function be called? ```javascript function mystery(n) { if (n <= 1) return 1; return mystery(n - 2); } mystery(5); ``` #### --distractors-- 2 --- 5 --- 4 #### --answer-- 3 ### --question-- #### --text-- Which of the following is true about recursion? #### --distractors-- It should never have a base case. --- It should only be used for the Fibonacci sequence. --- It should only be used for factorials. #### --answer-- It should always have a base case. ### --question-- #### --text-- Which of the following options would be an appropriate base case for the given example? ```js function countDownToZero(number) { // Base case goes here. console.log(number); countDownToZero(number - 1); } ``` #### --distractors-- ```js if (number > 0) { return; } ``` --- ```js if (number !== 0) { return; } ``` --- ```js if (number === 0) { return; } ``` #### --answer-- ```js if (number < 0) { return; } ``` ### --question-- #### --text-- Why must recursion have a base case? #### --distractors-- To ensure the function always has a return value. --- To reduce the number of function calls. --- To ensure all recursive calls are executed in the correct order and a `RecursionError` is not thrown. #### --answer-- To provide a way for the function to break out of its recursive calls and prevent infinite loops. ### --question-- #### --text-- What will this recursive function do? ```js function repeatString(str) { return str + repeatString(str); } ``` #### --distractors-- Return the string twice. --- Return `undefined`. --- Create an empty string. #### --answer-- Cause a stack overflow. ### --question-- #### --text-- What is a call stack? #### --distractors-- A list of function calls that have been executed. --- A list of values that were returned by a function. --- A special function used to call a function exactly three times. #### --answer-- A data structure that keeps track of function calls and their execution order. ### --question-- #### --text-- What does this recursive function do? ```js function changeString(str) { if (str === "") return ""; return changeString(str.slice(1)) + str[0]; } ``` #### --distractors-- Duplicates a string. --- Removes vowels. --- Removes spaces. #### --answer-- Reverses a string.