This community-built FAQ covers the “Semi-Prime Numbers” code challenge in JavaScript. You can find that challenge here, or pick any challenge you like from our list.
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Solution to the problem-
function checkPrime(n){
for (let i=2; i<=n/2; i++){
if(n%i==0){
return false;
}
}
return true;
}
function checkSemiPrime(number) {
let divisors=[];
for (let i = 2; i * i <= number; ++i){
if (number % i == 0) {
divisors.push(i);
if (i != number / i) divisors.push(number / i);
}
}
let isPrime=true;
if(divisors.length){
for (let j = 0; j < divisors.length; ++j){
if(!checkPrime(divisors[j])){
isPrime=false
break;
}
}
}
if(isPrime && divisors.length){
return true;
}
return false;
}
function semiPrimeCount(n) {
let counter=0;
for (let i = 4; i < n; ++i){
if(checkSemiPrime(i)){
counter++;
}
}
console.log('count',counter)
return counter;
}
semiPrimeCount(10);
// Leave this so we can test your code:
module.exports = semiPrimeCount;
1 Like
function semiPrimeCount(n) {
let res=;
let doublon=true;
let z=null;
for (let x=2;x<n;x++) {
if(primenumber(x)){
for (let y=2;y<n;y++) {
if(primenumber(y)) {
z=x*y;
doublon=res.some(a => a==z);
if(doublon==false && z < n) res.push(z);
}
}
}
}
return res.length;
}
function primenumber(x){
if(x < 2) return false;
for (let i = 2; i <= Math.sqrt(x); i++) {
if (x % i == 0) return false;
}
return true;
}
semiPrimeCount(10);
// Leave this so we can test your code:
module.exports = semiPrimeCount;
function semiPrimeCount(n) {
// pArray represents possible prime numbers
const pArray = [];
//Get prime Numers and put in pArray
for (let i=2; i<n; i++) {
//number to be divided by
let isPrime = true;
for (let j=Math.ceil(i/2); j>1; j--) {
if (i === j) {
continue;
} else if (i%j === 0) {
isPrime = false;
break;
}
}
if (isPrime) {
if (!pArray.includes(i)) {
pArray.push(i);
}
}
}
// Calculate and count semiPrimes
let count = 0;
let semiPrimes = [];
for (let x= 4; x<n; x++) {
//y is index of pArray
for (let y = 0; y < pArray.length; y++) {
let semiPrime = false;
if (!semiPrime) {
// z is other index of pArray to multiply by y
for (let z = 0; z<pArray.length; z++) {
if ((pArray[z] * pArray[y] === x) && !semiPrimes.includes(x)) {
semiPrimes.push(x)
count++;
semiPrime = true;
break;
}
}
}
}
}
console.log(count);
return count;
}
semiPrimeCount(10);
// Leave this so we can test your code:
module.exports = semiPrimeCount;
