What will this code output?

Question

BlackTom AI · Accepted Answer

The code defines a recursive function mystery(x) with a base case: if x == 0, return 0. Otherwise, it returns x + mystery(x - 1). This creates a sum of all integers from x down to 1.

Option 3: If we trace mystery(3), we get 3 + mystery(2). Then mystery(2) = 2 + mystery(1), and mystery(1) = 1 + mystery(0). mystery(0) returns 0. So the total is 3 + 2 + 1 + 0 = 6. Therefore, the output is not 3.

Option 6: This matches the computed total for mystery(3) as shown above. The expression expands to 3 + 2 + 1 + 0, which sums to 6, so this option aligns with the actual output.

Option Error: The recursion has a well-defined base case at x == 0, so the function does terminate and does not raise an error for x = 3. Therefore, this choice is incorrect.

Option 9: There is no step in the expansion that yields 9; the sum from 3 down to 0 is 6, not 9. This option misstates the accumulation.

Option 0: The base case returns 0 only when x is 0, but the initial call is with x = 3, and the sum includes 3, 2, and 1 before reaching 0, so the result is not 0.

IS 4485-001 Fall 2025 Final Exam Practice 2

What will this code output?

查看解析

登录即可查看完整答案

类似问题

Which of the following code snippets returns the factorial of a given number? (Hint: Factorial of 5 = 5! = 1 * 2 * 3 * 4 * 5 = 120)

Which of the following code snippets returns the factorial of a given number? (Hint: Factorial of 5 = 5! = 1 * 2 * 3 * 4 * 5 = 120)

What is a base case in recursion?

What will this recursive function print when called with countdown(3)?

Which of the following situations might cause a recursive function to run infinitely?

What will be the output of this recursive function call factorial(4)?

Which best describes recursion?

What will this code output?

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单