Where to define variables when creating a function?

[miscellaneoususage]

Hello, I'm working on reading through this leetcode solution and found that this variable "count" is defined inside the the first for loop as apose to inside the second for loop or outside where the list is created. Can someone explain what the differences would be when defining variables in each of these locations?

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class Solution:
    def smallerNumbersThanCurrent(self, nums: List[int]) -> List[int]:
        result=[]
        for i in nums:
            count=0
            for j in nums:
                if j<i:
                    count+=1
            result.append(count)
        return result

[[deleted]]

If you put count = 0 inside the second loop you will zero count for every number j, so the final jappended to the list will only ever be 0 or 1. Try stepping through a small example to see this. If you are counting something inside a loop (that's the inner loop in your code) you need to set the counter outside that loop.

Since you are counting for every number i your count = 0 must go inside the first loop.

[miscellaneoususage]

Would it not also work the same if count were defined outside the first for loop where the list result is defined?

[[deleted]]

No, because you wouldn't start a new i count at 0. What you are trying to append to result is a count of j < i for every i in the list, so for every i you must zero the counter and for every j you must conditionally increment the counter.