Question

Today, I went for an interview and the interviewer asked me how I would find the index of a given value (number) in a pre-sorted array like this:

$preSortedArr=array(23,32,36,41,45,54);

He also said that using recursion is not allowed.

I think the function should look like this:

function findIndexByValue($preSortedArray,$value){            
//some codes here       
}

What solution do you think he was expecting from me?

EDIT: Sorry, I forgot to add that he originally asked me to write pseudocode, but I said I didn’t know. Then I tried to write it in PHP, but I think he’s expecting a language-independent solution.

Answer 1

Since he said the array was pre-sorted, he was probably expecting a binary search. A linear search (with a possible optimisation since the array is sorted – exit with failure if you find a larger value) would of course be perfectly fine on the small array in the example. Probably faster, if it matters.