Problem 6

4 thoughts on “Problem 6”

1. /*
    * File: Hailstone.java
    * Name: 
    * Section Leader: 
    * --------------------
    * This file is the starter file for the Hailstone problem.
    */
   
   import acm.program.*;
   
   public class Hailstone extends ConsoleProgram {
   	private static final int THE_END = 1;
   
   	private int a = 0;
   	private int counter = 0;
   	
   	public void run() {
   		
   	a = readInt("Enter a number: ");	
   		
   	while (a!=THE_END){
   		counter++;
   		if (a%2==0){
   			//for even number
   			a=a/2;
   			println(a + " is even, so I take half: "+a);
   		} else {
   			//for odd number
   			a=(a*3)+1;
   			println(a + " is odd, so I make 3n+1: "+a);
   		}
   	}	
   		println ("It took " + counter +" times.");
   	}
   }
   

2. If you enter a negative integer or zero, it goes into an infinite loop.

   if(input <= 0) {break;}

   Richard Curtis, you are displaying the same integer twice.

3. I think the infinite loop caused by zero or negative integer can be avoided just by changing
   while(n != 1) to while(n > 1)
   this will be better, i guess.

4. my method here:

   /*
    * File: Hailstone.java
    * Name: 
    * Section Leader: 
    * --------------------
    * This file is the starter file for the Hailstone problem.
    */
   
   import acm.program.*;
   
   public class Hailstone extends ConsoleProgram {
   	public void run() {
   		while (true){
   			int n,m,steps;
   			steps = 0;
   			m = 0;
   			n = readInt("Enter a number ");
   			while (n > 1 ) {	/*i use "n>1" instead of "n!=1"just to make
   								sure the program won't run infinitely*/
   				steps++;
   				/*Even*/
   				if ((n%2) == 0) {
   					m = n/2;
   					println(n +" is even, so it's devided by two :" + m);
   					n = m;
   				} else {
   					/*odd*/
   					m = n*3+1;
   					println(n +" is odd, so i make 3n+1 :" +m);
   					n = m;
   			}
   		}
   		println("The program takes " + steps + " to reach " + n +".");
   		}
   	}
   }