Basic threshold stop
Input
take_until([1, 2, 3, 4], 5)
Output
[1, 2, 3]
Cumulative sums: 1, 3, 6. 6 >= 5 at the third element, so return [1, 2, 3].
Full lesson preview
Repeat Until Condition Met
Iterate through a sequence and collect items until a cumulative condition is satisfied.
Python practice6 minLoops & IterationBeginnerLast updated March 15, 2026
Problem statement
Given a list of numbers and a threshold value, return a list containing the prefix of numbers taken from the start of the list up to and including the element that makes the cumulative sum reach or exceed the threshold. If the threshold is less than or equal to zero, return an empty list. If the threshold is never reached, return the entire input list.
Task
Use a loop to accumulate values and stop when a condition (threshold) is met.
Examples
Input format
A list of integers (nums) and an integer (threshold).
Output format
A list of integers representing the prefix up to the threshold condition.
Constraints
Do not use external libraries. Preserve original order. Time complexity should be O(n).
Samples
Sample 1
Input
take_until([10, -1, 5], 8)
Output
[10]
10 >= 8 immediately, so only the first element is returned.