Question

How to calculate the Collatz sequence starting with 13 in Java

Answer 1

public class MyClass {
    // Collatz Sequence Example:
    // 13 - 40 - 20 - 10 - 5 - 16 - 8 - 4 - 2 - 1
    
    private static long CalcCollatz(long x) {
    	// if (number is odd) return x*3 + 1
    	// if (number is even) return x/2 
    	if ((x & 1) != 0) { // odd
    		return x * 3 + 1;
    	}
    	return x / 2; // even
    }
    
    private static void PrintCollatzSequence(long x) {
    	System.out.print(x + " ");

    	while (x != 1) {
    		x = CalcCollatz(x);
    		System.out.print(x + " ");
    	}
    }

    public static void main(String args[]) {
        long x = 13;

	    PrintCollatzSequence(x);
    }
}





/*
run:
    
13 40 20 10 5 16 8 4 2 1 
 
*/

 

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