59 lines
1.8 KiB
Java
59 lines
1.8 KiB
Java
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import java.util.Arrays;
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import java.util.Scanner;
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public class SieveOfErathostenes {
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private static void isValid(String input) {
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if (input == null) {System.exit(-1);}
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try {
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Integer.parseInt(input);
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} catch (NumberFormatException nfe) {
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System.out.println("Die eingegebene Zahl ist keine ganze Zahl");
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System.exit(-1);
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}
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int cleanInput = Integer.parseInt(input);
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if (cleanInput < 2 || cleanInput > 1000) {
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System.out.println("Die eingegebene Zahl muss mindestens 2 sein und höchstens 1000 sein.");
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System.exit(-1);
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}
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}
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private static void printArray(boolean[] arr) {
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for (int i = 0; i < arr.length; i++) {
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if (arr[i]) {
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System.out.printf("%d ", i + 2);
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}
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}
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System.out.printf("%n");
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}
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public static void main(String[] args) {
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//System.out.println("Sanity Check");
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Scanner input_scanner = new Scanner(System.in);
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System.out.println("Bitte gib eine Zahl ein. ");
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String user_input = input_scanner.nextLine();
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input_scanner.close();
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isValid(user_input);
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int clean_input = Integer.parseInt(user_input);
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boolean[] primes = new boolean[clean_input];
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Arrays.fill(primes, true);
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for (int i = 1; i < clean_input; i++) {
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if (i == 1) {continue;}
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if (primes[i]) {
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for (int j = 2; j < clean_input; j++) {
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int tmp = j*i;
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if (tmp > clean_input) {
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break;
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}
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primes[tmp - 2] = false;
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}
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}
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}
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primes[clean_input - 1] = false;
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printArray(primes);
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}
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}
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