Question

There is an array and the distance between any two consequent elements is one (+1/-1). How will you find an element in it. Can it be done in less than O(n) time

Answer 1

Simply start in first position; now consider the difference bewteen the searched number m; if array[0] == m then we finished; otherwise we have to jump of abs(array[0] - m) positions; now just repeat this until the end of the array.

However, in the worst case we can’t do better than O(n), just consider this case, we want to find 11:

10 9 8 9 8 9    10 9 8 9 8 9    10 9 8 9 8 9    10 9 8 9 8 9