JavaScript Algorithms - 9 - Prime Number

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Prime Number Algorithm
JavaScript Algorithms
Algorithms with JavaScript

[ogucharles]

Thanks a lot for the lessons. Anticipating for the next class.

[xitri]

Wow the optimize way of doing it really humbled me down. I learnt that there's always more optimize and better way of writing code.

[ajayraja]

Could you please Zoom in replit for next video? My eye needs to zoom in for that theme

[gabrieludo]

Thanks, sir, you deserve 1Million plus subscribers

[veryhightower]

Hello. Thank you very much for your videos. I learn algorithms with your playlist. And also recording videos with this progress and with my solves.

[jeremiahojo]

😂Never seen a more complicated definition of prime numbers

[roebucksruin]

The square root trick is interesting, but does it actually optimize the function? The first instance where n % i === 0 will trigger the return statement, so all future loops will not run.

[night-knight_]

the % is not "devide by" it's "remainder" the devide by operator is this "/". They are not the same

[davidpokrajac]

What if for example we put 1 as the parameter...first if statement is success and we return false...would it be then consant O(1) time complexity?

[abhisheksharma]

function isPrime(n) {
if (n === 2) {
return true;
}
for (let i = 2; i < n; i++) {
if (n % i === 0) {
return false;
}
}
return true;
}

[CrouTonG]

function isPrime(n) {
if (n < 2) return false
else if (n % 2 !== 0 || n === 2) return true

return false
}

[piotrekjazz]

Second solution would be more optimal if the loop wasn't stopped by return, otherway math function only adds extra calculations, both solutions are at most O(sqrt(n))

[damo]

Sir, the value of 'this' is lexical(static) scoped or dynamic scoped? I have a confusion. I think it's dynamic scoped because it gets its value through execution context. But I have already learned, JavaScript only uses lexical scope

[manishaggarwal]

can't i do in for loop i < (n / 2 + 1);
this will reduce our steps

[nicolauk]

function isPrime(n) {
let cont = 0
for (let i=1; i<=n; i++) {
if(n%i == 0){
cont++
}
}
return cont == 2
}

[Avatar-Roku]

Hey I have a little confusion in the code..When inside the for loop, I use the if condition for n%i===0 and then inside the for loop only I use the return true in an else condition, it returns wrong values for numbers like 2 and 55..but works perfect if I do as the tutorial...any idea where I am doing wrong?

[oussamahamdi]

And i think we can check if n > 2 && isEven then we return false because all Prime numbers except for 2 are Odd.

[demno]

Amazing tutorial as always expect ; thanks a lot but I have bug in prime(2)

[ojooladimeji]

function primeNumber(n){
for (i = 2; i < n; i++){
if (n % i || n===2){
return ' Prime Number'
}
else {
return ' Not a Prime Number'
}
}
}

[reactworld]

second solution does not work like if you put 9 then it will check only up to 3 and 3 is prime number and 9 is not prime number