algorithm - Binary search on unknown size array -


suppose array has been given , want find element in array , how can search element in array using binary search , given array sorted , size of array unknown. linear search can applied trying figure out faster search linear algorithm.

if can test whether have fallen out of array range, use modified binary search (assume 1-based array):

  1. lower = 1, upper = 1;
  2. while (a[upper] < element) upper *= 2;
  3. normal binary search on (lower, upper).

otherwise, there no real way it: assume find somewhere equals element need, cannot know if falls out of array.


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