Last active
May 14, 2020 00:50
-
-
Save ababup1192/cb7883b01307ea7c09573e054b97a329 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import java.math.BigInteger; | |
| import java.util.ArrayList; | |
| import java.util.Date; | |
| // Collatz.check() checks the Collatz conjecture for a given | |
| // number n. | |
| // Now, to prove the conjecture to be correct, we would need to | |
| // to verify it for all n. | |
| // This is not possible to check for all n with a given computer | |
| // but at least we can check for several values. | |
| // | |
| public class CheckCollatz { | |
| private final static BigInteger ONE = new BigInteger("1"); | |
| // Check the conjecture for 1 <= i <= n | |
| public static boolean check(BigInteger n) { | |
| // TODO complete | |
| int core = Runtime.getRuntime().availableProcessors(); | |
| BigInteger s = n.divide(new BigInteger(String.valueOf(core))); | |
| ArrayList<CalcCheckCollatz> threadList = new ArrayList<>(); | |
| for (int i = 0; i < core; i++) { | |
| CalcCheckCollatz calcCheckCollatz = new CalcCheckCollatz(new BigInteger(String.valueOf(i)).multiply(s), | |
| new BigInteger(String.valueOf(i)).multiply(s).add(s).subtract(ONE)); | |
| calcCheckCollatz.start(); | |
| threadList.add(calcCheckCollatz); | |
| } | |
| for (CalcCheckCollatz calcCheckCollatz : threadList) { | |
| try { | |
| calcCheckCollatz.join(); | |
| } catch (Exception e) { | |
| e.printStackTrace(); | |
| } | |
| } | |
| return true; | |
| } | |
| public static void main(String[] args) { | |
| if (args.length != 1) { | |
| System.out.println("Usage:"); | |
| System.out.println("java CheckCollatz n"); | |
| System.out.println("will check the Collatz conjecture for"); | |
| System.out.println("every 1 <= i <= n"); | |
| System.exit(1); | |
| } | |
| long start_time = new Date().getTime(); | |
| boolean v = CheckCollatz.check(new BigInteger(args[0])); | |
| long end_time = new Date().getTime(); | |
| System.out.println("Ellapsed time: " + (end_time - start_time) + "ms"); | |
| if (v) { | |
| System.out.println("The conjecture seems valid up to n=" + args[0]); | |
| } else { | |
| System.out.println("The conjecture is not valid"); | |
| } | |
| } | |
| } | |
| class CalcCheckCollatz extends Thread { | |
| private BigInteger lower; | |
| private BigInteger upper; | |
| CalcCheckCollatz(BigInteger lower, BigInteger upper) { | |
| this.lower = lower; | |
| this.upper = upper; | |
| } | |
| @Override | |
| public void run() { | |
| while (upper.compareTo(lower) > 0) { | |
| boolean result = Collatz.judgmentResult(upper); | |
| if (!result) { | |
| return; | |
| } | |
| upper = upper.subtract(BigInteger.ONE); | |
| } | |
| } | |
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| public class ThreadSample { | |
| public static void main(String[] args) { | |
| int core = Runtime.getRuntime().availableProcessors(); | |
| int n = core * 10; | |
| int s = n / core; | |
| System.out.println(core); | |
| System.out.println(n); | |
| System.out.println(s); | |
| for (int i = 0; i < core; i++) { | |
| new CalcCollatz(i * s, i * s + s - 1).start(); | |
| } | |
| } | |
| } | |
| class CalcCollatz extends Thread { | |
| private int lower; | |
| private int uppper; | |
| CalcCollatz(int lower, int upper) { | |
| this.lower = lower; | |
| this.uppper = upper; | |
| } | |
| @Override | |
| public void run() { | |
| System.out.println("lower = " + lower + " upper = " + uppper); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment