Better ways of counting the zeros?

Question

https://code.sololearn.com/Wm0CPovm9N4L/?ref=app
(this code may not work with everyone)
I was told there are better ways of counting the trailing zeros in this code. How?

Answer 1

hi Daniel,
you were told most probably to look for alternative ways coz right now you are doing way more computation for the problem.

maintaining a number array,
multiply its values
converting result to string
finding trailing zeroes.

For this problem, the goal is just to find the power of 5 in n!, coz
5 * 2 is 10, and since 2 is abundant so 5 will decide the number of zeroes.

so find a algorithm to find 5's power in n!, thats the answer.

Answer 2

Or better way without output null checking, sure match method.

var numZeros1 = prod.match(/0*$/)[0].length;

Answer 3

Try this

var match = prod.match(/0+$/);
var numZeros = match? match[0].length:0;

https://code.sololearn.com/Ws6j0g6BDznH/?ref=app

Answer 4

Morpheus That's why I tried using regular expressions first. But I couldn't get it to work so I settled for what I have now. It works, but still wanted to figure out the best way.

I'll try Calviղs way and your way.

Answer 5

If you're comfortable with regex, you could use a regex to match just zeroes at the end of a string, using $ as a right-side anchor.

For example, if I wanted to match "earn":
"SoloLearn".match(/earn$/)
...then use .length on the answer to see how many characters were matched.

Since you want to match an arbitrary number of zeroes, you may to use special matchers (e.g.: */+ to repeat 0/1 or more occurrences of the previous token), but the $ as a pattern anchor would stay in the same spot.

If you go this route, make sure you handle the case where there is no match (null.length is a TypeError)

Answer 6

Can I have an example of this?

I initially wanted to use a regex but i'm awful at them. Lol.