python - 幸运七人组，数组中 3 个连续数字的总和 == 7

Question

Write a function lucky_sevens(numbers), which takes in an array of integers and returns true if any three consecutive elements sum to 7.

为什么这没有产生 True 的输出？最后 3 个值总和 = 7。

 def lucky_sevens(numbers):
      x, y = 0, 3
      sum_of_numbers = sum(numbers[x:y])
      while (sum_of_numbers != 7) and (y < len(numbers)):
        x = x + 1
        y = y + 1
      if sum_of_numbers == 7:
        return True
      else:
        return False

    print(lucky_sevens([1,2,3,4,5,1,1]))

Answer 1

问题是，当函数首次被调用时，sum_of_numbers 变量被分配了列表中前 3 个值之和的值，并且永远不会用新的 x< 进行更新,y 值，您可能希望创建一个回调函数来实现该行为。

就目前情况而言，您需要将 sum 语句移至 while 循环中，以便使用新的 x 更新总和,y 值:

def lucky_sevens(numbers):
    result = False
    x, y = 0, 3

    while (y <= len(numbers)):
        if sum(numbers[x:y]) == 7:
            result = True
            break
        x += 1
        y += 1
    return result

print(lucky_sevens([1,2,3,4,5,1,1]))