Collective Health HackerRank OA

Collect Health Software Engineer OA
要求在20分钟内完成所有的题目，不能copy 和paste答案。题目都比较基础，现场搜google 有点来不及。还是靠自己平时的积累。里面有好几套题。我因为时间紧张，就选第一套来完成了。

时间复杂度

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func removeChar (String input, String illeagePattern) {
     for (char x : illeagePattern) {
         input.remove(x);
     }
}

选项有 O(n), O(2n), O(nm), O(nlogn) 我选的 O(nm);

unit test

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"signal failure within a unit test"  
题干没记全，这题没把握，我选的是 assert  

参考： Wikipedia: It is generally possible to perform unit testing without the support of a specific framework by writing client code that exercises the units under test and uses assertions, exception handling, or other control flow mechanisms to signal failure

coding question

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var add: () -> Int = {
  var counter = 0;
  return {counter = counter + 2; return counter}
}()
print(add())
print(add())

运行输出结果是？
备选项有
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4
我给的答案是 None of above

HTTP From the list of http methods please select ALL that are reasonable to alter data: 我给的是 post, put, delete
coding question

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func multiplyPriors(n: Int) -> Int {
  switch n {
  case 0:
    return 1
  case 1:
    return 2
  default:
    return multiplyPriors(n-1) * multiplyPriors(n-2)
  }
}

算法复杂度是____
选项是 O(n), O(2n), O(n^2), O(nlogn)

分析上述程序，可能的结果
我选的是 stack overflow when large n
计算结果 multiplyPriors(4)=_____
我的答案是 8
n/a
给出orders表

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 ----------------------------
name             |  type
orderNumber (pk) |  number
Status           |  varchar50
 ----------------------------
-- Status = 'Shipped'
-- 求所有没有shipped订单数
select count(*) from ORDERS where status <> 'Shipped';  

求top 5的没有shipped的订单
select * from ORDERS where status <> ‘Shipped’ limit 5;

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