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6.1. While: List of squares

pole55
pole55

"For a given integer N, print all the squares of positive integers where the square is less than or equal to N, in ascending order."

Example input
50

Example output
1 4 9 16 25 36 49

4 years ago
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2
girianshiido
girianshiido

I think it's better to use a while loop here.
For example, if x is one million, the last number of the list will be one million, but you'll compute the square of each number from one to one million (so the last square will be one trillion).

x = int(input("Enter the number:")) i = 1 while i*i <= x: print(i*i) i += 1
4 years ago
1
pole55
pole55

@girianshiido
This code publishes only squares which are less than a given number. We have "if i**2 <= x" here for this. it is equal to your "while i*i <= x". just try it // Link to the task: https://repl.it/student/submissions/3764967

4 years ago
1
girianshiido
girianshiido

@pole55
what I meant is that your script is computing too much stuff for its purpose. That's because range(1, x+1) is way too big, especially if x itself is big. If x=10^10, then you only really need to stop at 10^5, because the square of this number is 10^10.
Here is a modification of your own script:

from math import sqrt x = int(input("Enter the number: ")) print("All the squares in the given range are:") print([i**2 for i in range(1, int(sqrt(x))+1) if i**2 <= x])

Try your script with x = 10000000000 and try this new version. You'll see the difference.

4 years ago
1
pole55
pole55

@girianshiido
, my code gives the same result
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4 years ago
1
pole55
pole55

its all because of "if i**2 <= x" that tells to stop at "10^5" (in your words). without this part, it will print "10^10".

4 years ago
1
girianshiido
girianshiido

@pole55
Did you try your code with 10000000000?
Your code doesn't tell to stop at 10^5. It'll try to compute each square from 1 to x², even if i² is already greater than x. Of course, none of these numbers will be in the list, because they don't verify the condition.

4 years ago
1
pole55
pole55

@girianshiido
the result does not depend on the value of the number. they are still identical. p.s.: I use here a million cause the computer hangs trying to work with 10000000000)). in both, my and yours, cases.
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Cannot infer image mime type

4 years ago
1
pole55
pole55

@girianshiido
oh. now i see what you are talking about! hmm. thanks

4 years ago
2
girianshiido
girianshiido

@pole55
I know they’re identical. On my 2011 MBA, it takes forever with your code but it works instantly with the sqrt.
By the way, I just realized I forgot to remove the unnecessary condition if i^2 <=x.

print([i*i for i in range(1, int(sqrt(x))+1)])
4 years ago