voyager-bit

Your mission

Find the single bit that differs between what came back and what should have.

today's brief

April 22, 2010. Voyager 2 is nearly 14 billion kilometres out and its science data starts coming back as nonsense, packet after packet. Engineers dumped the whole flight data system memory and compared it with what should have been there: one bit had flipped from 0 to 1, and that bit set the packet format. They reset it. The data came back clean and the probe is still sending. Find the flipped bit.

See it in action

flipped_bit(5, 4)

Expected result

Your checklist

For your own tracking. Tests grade your code.

got and want are non-negative.
Return the position of the one bit that differs, counting from 0 at the least significant end.
Return -1 when the two words are the same.
Return -1 when more than one bit differs.

More examples

flipped_bit(5, 5)

Expected result

-1

flipped_bit(3, 0)

Expected result

-1

Constraints

Expected files

flip.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions

voyager-bit

Your mission

Find the single bit that differs between what came back and what should have.

today's brief

See it in action

flipped_bit(5, 4)

Expected result

Your checklist

For your own tracking. Tests grade your code.

got and want are non-negative.
Return the position of the one bit that differs, counting from 0 at the least significant end.
Return -1 when the two words are the same.
Return -1 when more than one bit differs.

More examples

flipped_bit(5, 5)

Expected result

-1

flipped_bit(3, 0)

Expected result

-1

Constraints

Expected files

flip.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions