Interview Question : Trim multiple consecutive spaces from a string

Question

This is an interview question Looking for best optimal solution to trim multiple spaces from a string. This operation should be in-place operation.

input  =          


        

Answer 1

I'd propose a little state machine (just a simple switch statement). Because if the interviewer is anything like me, the first enhancement they'll ask you to do is to fully trim any leading or trailing spaces, so that:

"    leading and    trailing    "

gets transformed to:

"leading and trailing"

instead of:

" leading and trailing "

This is a really simple modification to a state-machine design, and to me it seems easier to understand the state-machine logic in general over a 'straight-forward' coded loop, even if it takes a few more lines of code than a straight-forward loop.

And if you argue that the modifications to the straight forward loop wouldn't be too bad (which can be reasonably argued), then I (as the interviewer) would throw in that I also want leading zeros from numbers to be be trimmed.

On the other hand, a lot of interviewers might actually dislike a state-machine solution as being 'non-optimal'. I guess it depends on what you're trying to optimize.