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recursion.js
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53 lines (47 loc) · 1.47 KB
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// Complete the following functions.
// https://www.sitepoint.com/recursion-functional-javascript/
// see https://medium.com/developers-writing/fibonacci-sequence-algorithm-in-javascript-b253dc7e320e
const nFibonacci = (n) => {
// fibonacci sequence: 1 2 3 5 8 13 ...
// return the nth number in the sequence
// check if base case and return
if (n <= 1) return 1;
// otherwise we know Fibonacci(n) is made of up Fib(n-2) + Fib(n-1) which is recursive
return nFibonacci(n - 1) + nFibonacci(n - 2);
};
const nFactorial = (n) => {
// factorial example: !5 = 5 * 4 * 3 * 2 * 1
// return the factorial of `n`
if (n < 2) return 1;
return n * nFactorial(n - 1);
};
/* Extra Credit */
const checkMatchingLeaves = (obj) => {
// return true if every property on `obj` is the same
// otherwise return false
let testVal;
let litmus = true;
// create a test to see if the key of the object is another object. if yes, recurse
const checkLeaves = ((tree) => {
Object.keys(tree).forEach((key) => {
if (testVal === undefined && typeof tree[key] !== 'object') {
testVal = tree[key];
return undefined;
}
if (typeof tree[key] === 'object') return checkLeaves(tree[key]);
if (tree[key] !== testVal) {
litmus = false;
return undefined;
}
return undefined;
});
});
checkLeaves(obj);
return litmus;
};
/* eslint-enable no-unused-vars */
module.exports = {
nFibonacci,
nFactorial,
checkMatchingLeaves,
};