What the code does is not its running time
Goal: Describe the intended result before calculating work.
Consider this task: if a > b, add the even values; otherwise add the odd values. This describes what the code is meant to compute. Even values are divisible by 2; odd values are not.
To analyze time, we need more information: how many values are processed, and how much work is done for each one?
Suppose the first branch processes n values, the second processes m values, and each value takes constant work. Only one branch runs. If either branch is possible, the worst-case time is as the sizes grow.
Read incomplete pseudocode carefully
if a > b
for (i 0 → n)
Sum(even)
else
for (i 0 → m)
Sum(odd)
This is shorthand, not a complete executable program. It does not fully define Sum or the exact loop bounds. We cannot use it alone to prove an exact number of operations.
The analysis above explicitly assumes n or m iterations and constant work per iteration. If Sum scans a whole list on every call, that call has its own cost and we must include it.
When asked for the code's purpose, describe its result. Repeating the words “if” and “for,” or writing only a complexity expression, does not explain what it computes.
Remember: Purpose and running time are two separate questions.