過敏

過敏

給定一個人的過敏分數,判斷他們是否對特定項目過敏,並列出他們完整的過敏清單。
深入探索 過敏!

我們會探索位元位移、位元比較以及其他二進位數字的概念!我們也會看看一個使用模式比對的解法,以及在 Erlang 中用遞迴的有趣做法。

說明

Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.

An allergy test produces a single numeric score which contains the information about all the allergies the person has (that they were tested for).

The list of items (and their value) that were tested are:

  • eggs (1)
  • peanuts (2)
  • shellfish (4)
  • strawberries (8)
  • tomatoes (16)
  • chocolate (32)
  • pollen (64)
  • cats (128)

So if Tom is allergic to peanuts and chocolate, he gets a score of 34.

Now, given just that score of 34, your program should be able to say:

  • Whether Tom is allergic to any one of those allergens listed above.
  • All the allergens Tom is allergic to.

Note: a given score may include allergens not listed above (i.e. allergens that score 256, 512, 1024, etc.). Your program should ignore those components of the score. For example, if the allergy score is 257, your program should only report the eggs (1) allergy.