JavaScript Algorithms - 7 - Fibonacci Sequence

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Fibonacci Sequence
JavaScript Algorithms
Algorithms with JavaScript

[ajiteshmishra]

I can't believe myself but I write it on paper in steps in bullet points and then write the code accordingly and it works wow it really boosts my confidence, feeling like a impostor for long time

[NadirAli-knsl]

function fibonacci(n) {
let series = []
if (n === 0) {
series.push(0)
} else {
series.push(0, 1)
}
for (let i = 2; i < n; i++) {
series.push(series[i - 1] + series[i - 2])
}
return series
}

[toluajise]

Thank you so much for this course. However I have a little observation for the loop condition. Take for example when n=7
This: for (let i = 2; i < n; i++) {
because your loop condition causes the loop to stop iterating before reaching the nth term. That't why we have
Should have been this I guess: for (let i = 2; i <= n; i++) {
This change ensures that the loop generates the Fibonacci sequence up to and including the nth term, as intended.
[
0, 1, 1, 2,
3, 5, 8
]
Since the Fibonacci sequence generated by the code starts from the 0th term and includes the 7th term. So, I think it should include a total of 8 terms.
[
0, 1, 1, 2,
3, 5, 8, 13
]
Please let me know if my observation is right.

[ankushladani]

/function fibbonacci(n) {
let a = 0;
let b = 1;
const arr = [];
for (let i = 0; i < n; i++) {
let c = a + b;
arr.push(a);
b = a;
a = c;
}
return arr;
}
console.log(fibbonacci(10);

We can use this way too.
Thank You sir for this awesome series.

[urmil]

understood the concept in just 4 mins, very good and easy explanation

[ROHAN]

Thank you! Exactly what I needed.
A short and simple explanation to revise algos.
Subscribed!!

[akay]

function fibonacci(n){
const fib=[0, 1];
for(let i=2; i<n; i++){
fib.push(fib[i-1] + fib[i-2]);
}
return fib;
}

This worked for me

[khairiyusoff]

function fibonacci(n) {
let output = [0, 1];
for (let i = 0; i < n - 2; i++) {
output.push(output[i] + output[i + 1]);
}
return output;
}

console.log(fibonacci(7)); //[0, 1, 1, 2, 3, 5, 8]
console.log(fibonacci(5)); //[0, 1, 1, 2, 3]
console.log(fibonacci(10)); //[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

[maahimaarrahahai]

Would like to add that fibonacci(1) would return [ 0, 1 ] which is incorrect. We can use an if condition to return the array as [ 0 ];

[pillo]

Thanks for this videos, i will watch all the course. Congrats for your work!

[kaissarmouelhi]

I think (might be wrong . Take it with a pinch of salt) it's important to mention that the fib array is likely to grow in the future. It depends on the input size of n. Here memory also consumes as much as the array requires. Space complexity is of O(n), too. This fact puts the function through critical interrogations since both time & space are heavily dependent on the input size.

[kjagan]

Sir please do a videos on data structures as well .

[jahnavitaskani]

thanks for these videos. These are so helpful

[akaris]

Using Recursion makes more sense for Fibonacci Sequencing

function fib(n){
if(n ===1 || n ===2){
return 1
}
return fib(n-1)+ fib(n-2)
}
console.log(fib(12)) // 144
console.log(fib(10)) // 10
console.log(fib(11)) // 89

[spreadingtheknowledgeoflight]

function fibbonacci(n) {
const fib = [0, 1];
var tmp = [];
if (n == 0) {
return tmp;
}
if (n == 1) {
tmp = tmp[0];
return fib;
}
for (let i = 2; i < n; i++) {
fib[i] = fib[i - 1] + fib[i - 2];
}
return fib;
}
console.log(fibbonacci(5));
console.log(fibbonacci(0));

[sskhekhaliya]

if we use while loop instead of for like:

while (arr.length < n){
arr.push(arr[arr.length-1] + arr[arr.length-2]);
}

then what will be Big-O time complexity, O(n^4)? because it is checking length every time four time and one time use push.

[shujaatali]

Thank you I have done my code using push method. and O(n) time complexity is linear.

[rohitbagadi]

You declared fib as a const then how does the value of fib change after loop iteration???

[Singh]

function fibbonaci(n){
const fibarr=[0, 1];
// console.log(fibarr.length);
for (let i = fibarr.length; i <n; i++) {

};
console.log(fibarr);
}

fibbonaci(1000);

[Lolwithforrest]

Do you recommend using semicolons or omitting them? Thank you for your work. I especially enjoyed your SvelteKit series.