3x+1 conjecture

Question

on my computer, I have the following script in the head:
<script>
var x = prompt("Choose a number");
var a = x%2; /* For testing if it is an even number */
var b = 0;
while(x!=1) {
switch (a) {
case 0:
x = (3*x)+1;
break;
case 1:
x = x/2;
}
var a=x%2;
++b;
}
</script>

And in the body I got this one:
<script>
document.write("It takes "b + "steps" + " for this number in the 3x+1-conjecture to reach one.");
</script>

And this didnt work. What did I do wrong?

Answer 1

oh sorry that was a typomistake in te comment. on my pc i have a semicolomb

Answer 2

maybe you need to round off the number a?

if the user picks x = 10.
then 3 * 10 + 1 is 31.
then a = 31 % 2 = 1.
then it loops.
because a is 1, x = 31 / 2 = 15.5.
then a = 15.5 % 2 = 1.5.
then it loops.
now the loop is stuck because a is neither 0 or 1, but 1.5.

you can round off a with either Math.floor(a), Math.ceil(a) or Math.round(a).

im guessing you need to use Math.floor(a).
Math.floor(1.5) = 1.

please note I have not tested this code.