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* I'am finished the homework #2

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* I'am finished the homework
Oct 15, 2019
49bc0e2
* I'am corrected mistakes in my homework
Oct 19, 2019
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54 changes: 26 additions & 28 deletions src/assignment0.js
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Original file line number Diff line number Diff line change
@@ -1,38 +1,36 @@
var num = parseInt(prompt('Enter a natural number or "exit"'));
var num = prompt('Enter a natural number or "exit"');
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@githuboftigran githuboftigran Oct 15, 2019

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At first glance it's not clear why this line is outside the loop. It's a bit confusing. If this line goes into top of while loop, the code will be clearer.


var c = 1;
var primeArr = [2];
var i = 3;
while (num !== 'exit') {

function isPrime(k) {
for (var j = 2; j < k; j++) {
if (k % j === 0) {
return false;
var count = 1;
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@githuboftigran githuboftigran Oct 15, 2019

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These numbers are confusing at first glance. Why 1 ? Why [2], why 3 ? I see your intention, but still, this is confusing. Please set count to 0, primeArray to empty array ([]) and startPrimeNum to 2. BTW add a comment to this line like:
var startPrimeNum = 2; // The first prime number
so it will be clear what this number is about.

var primeArr = [2];
var startPrimeNum = 3;

while (count < parseInt(num)) {
var isPrime = true;
for (j = 2; j < startPrimeNum; j++) {
if (startPrimeNum % j === 0) {
isPrime = false;
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@githuboftigran githuboftigran Oct 15, 2019

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This loop will do 998 iterations, if startPrimeNum is 1000.
But after first iteration it's clear, that 1000 is not prime, so it will be better to break; the loop once the condition is satisfied.

}
}
}
return true;
}

while (c < num) {
if (isPrime(i)) {
primeArr[c] = i;
c++;
if (isPrime) {
primeArr[count] = startPrimeNum;
count++;
}
startPrimeNum++;
}
i++;
}


console.log(primeArr);

for (let i = 0; i < primeArr.length - 1; i++) {
for (var j = 0; j < primeArr.length - 1; j++) {
if ((primeArr[j] % 10) > (primeArr[j + 1] % 10)) {
let c = primeArr[j];
primeArr[j] = primeArr[j + 1];
primeArr[j + 1] = c;
for (var i = 0; i < primeArr.length - 1; i++) {
for (var j = 0; j < primeArr.length - 1; j++) {
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I can see bubble sort implementation here, but both loops run from 0 to primeArr.length, so primeArr.length^2 operations will be performed. But if first loop starts at i, instead of 0, only (primeArr.length * (primeArr.length + 1)) / 2 operations will be performed, which is much better.

if ((primeArr[j] % 10) > (primeArr[j + 1] % 10)) {
var sort = primeArr[j];
primeArr[j] = primeArr[j + 1];
primeArr[j + 1] = sort;
}
}
}

console.log(primeArr);
num = prompt('Enter a natural number or "exit"');
}

console.log(primeArr);