org.onetwo.common.utils.MathUtils Maven / Gradle / Ivy
package org.onetwo.common.utils;
import java.util.ArrayList;
import java.util.List;
public final class MathUtils {
public static boolean isPrime(long n){
if(n<=1)
return false;
for(int i=2; (i*i)<(n+1); i++){
if(n%i==0)
return false;
}
return true;
}
public static long getPrime(int index){
if(index<0)
throw new IllegalArgumentException();
int pcount = 0;
long numb = 2;
while(true){
if (isPrime(numb)){
pcount++;
}
if(pcount-1==index)
break;
numb++;
}
return numb;
}
public static Long[] generatedPrimes(int primeCount){
int pcount = 0;
long numb = 2;
Long[] result = new Long[primeCount];
while(true){
if (isPrime(numb)){
result[pcount++]=numb;
}
if(pcount==primeCount)
break;
numb++;
}
return result;
}
public static Long[] generatedPrimesUntil(long maxNumber){
long numb = 2;
List primes = new ArrayList();
while(true){
if(numb>maxNumber)
break;
if (isPrime(numb)){
primes.add(numb);
}
numb++;
}
return primes.toArray(new Long[primes.size()]);
}
private MathUtils(){
}
}
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