8 ms·

Validator seems broken.

gamegoblin 13y ago
I keep getting various parse errors like Expected assignment, comment or return statement but " " found. When trying to get rid of parse errors, I did something like "return x" and it says Solution did not return correct output for x=1. Expected output: 1, got: 0 Which is clearly not right. Just tried doing "return 1" and still got Solution did not return correct output for x=1. Expected output: 1, got: 0
- dalke 13y ago
  I get the same thing as you, and I get the same thing when I have "return 0." The puzzle is annoying. For what it's worth, here's my answer: 1>>(x&~(~x+1))&~(1>>x) . (I didn't figure out that the tester was broken before I developed my answer.) I tested it with positive integers on Python. I haven't tried it with negatives in Javascript. The '(x&~(~x+1))' is a work-around to get 'x&(x-1)', which is 0 if x is a power of two. The (1>> value) is a workaround to get "value == 0". Thus, '1>>(x&~(~x+1))' means 'is x a power of two?' The ~(1>>x) means 'is x == 0'. Combine the two together gives 1 if a single bit is set, else 0.
  - letney 13y ago
    The work-around for 'x&(x-1)' I found is one-character longer: '(x&(~x+x+x))'
fourspace 13y ago
I certainly can't get it to work. For the first problem, I tried: function one_bit(x) { return x & (x-1) == 0 } Only to see this error: Expected "}" or comment but "&" found. WAT
- dalke 13y ago
  It appears to have a limited JS validator to prevent you from using anything other than the limited operators it allows.
  - sp332 13y ago
    It really doesn't like having anything after "return" except a single value or variable.
    - dalke 13y ago
      That's not it. For example, it accepts "return x|x&x;" . The restriction is that only a handful of Javascript operations are allowed. Anything else gives a hard-to-understand error message.
- wellingtons 13y ago
  You can't use '-'.
- warmfuzzykitten 13y ago
  That returns true or false, which I believe strictly speaking aren't numeric in Javascript. By definition of problem, probably should be: function one_bit(x) { return x & (x-1) == 0 ? 1 : 0; }
sachleen 13y ago
Definitely. function one_bit(x) { return 1 } Solution did not return correct output for x=1. Expected output: 1, got: 0 umm... ok
amenghra 13y ago
:( Oops, i'll fix it.
amenghra 13y ago
Should be fixed now...

I keep getting various parse errors like Expected assignment, comment or return statement but " " found. When trying to get rid of parse errors, I did something like "return x" and it says Solution did not return correct output for x=1. Expected output: 1, got: 0 Which is clearly not right. Just tried doing "return 1" and still got Solution did not return correct output for x=1. Expected output: 1, got: 0

dalke 13y ago
I get the same thing as you, and I get the same thing when I have "return 0." The puzzle is annoying. For what it's worth, here's my answer: 1>>(x&~(~x+1))&~(1>>x) . (I didn't figure out that the tester was broken before I developed my answer.) I tested it with positive integers on Python. I haven't tried it with negatives in Javascript. The '(x&~(~x+1))' is a work-around to get 'x&(x-1)', which is 0 if x is a power of two. The (1>> value) is a workaround to get "value == 0". Thus, '1>>(x&~(~x+1))' means 'is x a power of two?' The ~(1>>x) means 'is x == 0'. Combine the two together gives 1 if a single bit is set, else 0.
- letney 13y ago
  The work-around for 'x&(x-1)' I found is one-character longer: '(x&(~x+x+x))'

fourspace 13y ago

I certainly can't get it to work. For the first problem, I tried: function one_bit(x) { return x & (x-1) == 0 } Only to see this error: Expected "}" or comment but "&" found. WAT

dalke 13y ago
It appears to have a limited JS validator to prevent you from using anything other than the limited operators it allows.
- sp332 13y ago
  It really doesn't like having anything after "return" except a single value or variable.
  - dalke 13y ago
    That's not it. For example, it accepts "return x|x&x;" . The restriction is that only a handful of Javascript operations are allowed. Anything else gives a hard-to-understand error message.
wellingtons 13y ago
You can't use '-'.
warmfuzzykitten 13y ago
That returns true or false, which I believe strictly speaking aren't numeric in Javascript. By definition of problem, probably should be: function one_bit(x) { return x & (x-1) == 0 ? 1 : 0; }

sachleen 13y ago

Definitely. function one_bit(x) { return 1 } Solution did not return correct output for x=1. Expected output: 1, got: 0 umm... ok

amenghra 13y ago

:( Oops, i'll fix it.

amenghra 13y ago

Should be fixed now...