Question

我已经开始处理Daily Code逻辑问题，并且收到了第一个问题，这很简单，但是我不明白“一次完成”的意思。它只需要一行吗？如果是，在这个问题上怎么可能？那就是问题和我的代码：

##Good morning! Here's your coding interview problem for today.
##This problem was recently asked by Google.
##Given a list of numbers and a number k, return whether any two numbers from the list add up to k.
##For example, given [10, 15, 3, 7] and k of 17, return true since 10 + 7 is 17.
##Bonus: Can you do this in one pass?
def equivalent_sum(n,list_of_n):
  for x in list_of_n:
    for y in list_of_n:
      boolean = False
      if x != y:
        if x + y == n:
          boolean = True
        print("{} + {} {}".format(x,y,boolean))
l_of_numbers = [2,3,7,10,13,17,21]
equivalent_sum(20,l_of_numbers)

Answer 1

每秒钟==> O（n）时间复杂度

您将遍历该列表一次：

passed_nums = set() 
numbers = [2,3,7,10,13,17,21] 
k = 17 

def equivalent_sum(numbers):
    for num in numbers:
       diff = k - num
       if diff in passed_nums:
           return True
       passed_nums.add(num)
    return False

equivalent_sum(numbers)

或者您可以使用：

num_set = set(numbers)
any(k - e in num_set for e in numbers)

内建函数更快，因为它们在C代码上运行

这是什么意思？

1 个答案: