[viveksec]

Puzzle solving ability is a reliable indicator only if the candidate hasnt specifically prepared for them. Many Indian IT companies in the mid-late 90's conducted exams with difficult programming puzzles in them. This was great for a while, but soon those who wrote these exams told everyone else and the puzzle pool dried up. Future groups scored really well due to being better prepared against a known pool of puzzles. These days most IT companies have moved on to SAT/GRE style analytical problems.

Imagine your luck if you are at a Google interview and already know the Pascal triangle. You can just put up an act pretending to analyze various aspects before unveiling your grand solution.

If companies are merely using analytical ability as a filter, a SAT/GRE style exam will do better because the problem pool is much larger making it less vulnerable to preparation.