Mathematics I / Algorithms and Computational Thinking
Practice question · Select all that apply

Select every procedure below that FAILS to be a genuine algorithm.

Hints
  1. Test each against finiteness, definiteness and effectiveness in turn.
  2. One never stops, one cannot be followed unambiguously, and one is not a procedure at all.
Show the answer
  • B. Pick whichever move looks best and play it
  • D. The answer is the smallest x satisfying the equation
  • E. Start with x = 1 and repeatedly double it
Why

Doubling forever fails finiteness; 'looks best' fails definiteness; 'the smallest x satisfying the equation' is a specification with no procedure. The trial-division test and 'add 1 then stop' are both finite, definite and effective, so both are algorithms.

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