Which is missing? (2)

We handle lists that contain $n-1$ integers, all between $0$ and $n-1$ (both included), and all different. Therefore, exactly one of these $n$ numbers is missing. Which one?

Write a function $missing(lst)$ that receives such a list and returns the missing number.

Precondition: we are ensured that the list $lst$ received by the function will always fulfill the condition that it contains nonnegative integers less than $n$ , all different, where $n$ is one more than the length of $lst$ (hence, $n > 0$ is also guaranteed as the smallest list has length zero).

Problem information

Author: Jordi Petit (adapted by José Luis Balcázar)

Generation: 2026-01-25T17:09:38.335Z