CODEWITHSUNDEEP
python
user2709431
user2709431

Reputation: 51

Function running way too slow

I am practicing Python with Project Euler, question 1, but the function I wrote to solve it is taking way too long.

I figure it's because the way I coded it not the actual method itself.
When I run this function with 10 or 15 iterations it spits out an answer instantly, but as soon as I jump it up to even 20, it doesn't show me anything for even minutes.
This is obviously a big problem if I need to go to 1000 iterations.

def pe1(n):
    counter = 1
    total = 0
    while counter < n:
        if counter%3==0:
            total=total+counter
        if counter%5==0:
            if counter%3==0:
                continue
            total=total+counter
        if counter % 25 == 0:
            print (total)
        counter=counter+1
    return (total)

Upvotes: 5

Views: 124

Answers (4)

flyking_
flyking_

Reputation: 161

You can use table-driven. Like this.

counter_map = {3:fun1, 5:func2, 25:fun3} # key is remainder.Of course,fun can be replaced with lambda.

Upvotes: 0

bzdjamboo
bzdjamboo

Reputation: 565

To avoid traps like this one, consider using

if ...
elif ...
elif ...
else ...

Upvotes: 1

Amber
Amber

Reputation: 526593

Because as soon as counter hits 15, your loop goes into an infinite continue - it's always going to hit the second if statement's case.

You need to move your counter = counter + 1 line before the continue, or better yet, use something like for counter in range(1,n).

Upvotes: 6

Simon
Simon

Reputation: 10841

Consider the case if counter equals 15 and look at what happens where counter%5==0 and counter%3==0, which will first occur at that time.

Consider also what will not happen for that value of counter, specifically, the line counter=counter+1 won't be executed.

Upvotes: 2

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