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executable file
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Copy pathProblem003.js
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executable file
·50 lines (40 loc) · 881 Bytes
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function isPrime2(num) {
// alert(num);
if (isPrime.primeList.indexOf(num) != -1) return true;
for (var i=2;i <= num/2;i++) {
//alert('i = ' + i);
if (isPrime(i)) {
if ( num % i == 0 ) {
return false;
}
}
}
isPrime.primeList.push(num); // cache results
return true;
}
isPrime2.primeList = [2];
function lpf(num) {
for (var i=2;i <= num/2;i++) {
if (num % i == 0) {
if (isPrime(i)) {
var largestPrime = i;
}
}
}
if (!largestPrime) return num; //number is prime
return largestPrime;
}
function allPrimes(limit) {
var primes = [2];
function isPrime(x) {
for (var j in primes) {
if (x % primes[j] == 0) return false;
}
return true;
}
if (limit < 2) return null;
for (var i=3; i <= limit; i += 2) {
if (isPrime(i)) primes.push(i);
}
return primes;
}