aparler/RosettaCodeData
1
0
Fork 0
Code Issues 12 Pull requests 3 Projects Releases Packages Wiki Activity Actions

Data commit

Browse source
This commit is contained in:
Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
199093 changed files with 3378972 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

104
Task/Strong-and-weak-primes/Java/strong-and-weak-primes.java Normal file
View file

@ -0,0 +1,104 @@
public class StrongAndWeakPrimes {
private static int MAX = 10_000_000 + 1000;
private static boolean[] primes = new boolean[MAX];
public static void main(String[] args) {
sieve();
System.out.println("First 36 strong primes:");
displayStrongPrimes(36);
for ( int n : new int[] {1_000_000, 10_000_000}) {
System.out.printf("Number of strong primes below %,d = %,d%n", n, strongPrimesBelow(n));
}
System.out.println("First 37 weak primes:");
displayWeakPrimes(37);
for ( int n : new int[] {1_000_000, 10_000_000}) {
System.out.printf("Number of weak primes below %,d = %,d%n", n, weakPrimesBelow(n));
}
}
private static int weakPrimesBelow(int maxPrime) {
int priorPrime = 2;
int currentPrime = 3;
int count = 0;
while ( currentPrime < maxPrime ) {
int nextPrime = getNextPrime(currentPrime);
if ( currentPrime * 2 < priorPrime + nextPrime ) {
count++;
}
priorPrime = currentPrime;
currentPrime = nextPrime;
}
return count;
}
private static void displayWeakPrimes(int maxCount) {
int priorPrime = 2;
int currentPrime = 3;
int count = 0;
while ( count < maxCount ) {
int nextPrime = getNextPrime(currentPrime);
if ( currentPrime * 2 < priorPrime + nextPrime) {
count++;
System.out.printf("%d ", currentPrime);
}
priorPrime = currentPrime;
currentPrime = nextPrime;
}
System.out.println();
}
private static int getNextPrime(int currentPrime) {
int nextPrime = currentPrime + 2;
while ( ! primes[nextPrime] ) {
nextPrime += 2;
}
return nextPrime;
}
private static int strongPrimesBelow(int maxPrime) {
int priorPrime = 2;
int currentPrime = 3;
int count = 0;
while ( currentPrime < maxPrime ) {
int nextPrime = getNextPrime(currentPrime);
if ( currentPrime * 2 > priorPrime + nextPrime ) {
count++;
}
priorPrime = currentPrime;
currentPrime = nextPrime;
}
return count;
}
private static void displayStrongPrimes(int maxCount) {
int priorPrime = 2;
int currentPrime = 3;
int count = 0;
while ( count < maxCount ) {
int nextPrime = getNextPrime(currentPrime);
if ( currentPrime * 2 > priorPrime + nextPrime) {
count++;
System.out.printf("%d ", currentPrime);
}
priorPrime = currentPrime;
currentPrime = nextPrime;
}
System.out.println();
}
private static final void sieve() {
// primes
for ( int i = 2 ; i < MAX ; i++ ) {
primes[i] = true;
}
for ( int i = 2 ; i < MAX ; i++ ) {
if ( primes[i] ) {
for ( int j = 2*i ; j < MAX ; j += i ) {
primes[j] = false;
}
}
}
}
}