+- Hack Forums (https://hackforums.net)
+-- Forum: Tech (https://hackforums.net/forumdisplay.php?fid=444)
+--- Forum: Coding (https://hackforums.net/forumdisplay.php?fid=151)
+---- Forum: Software Development (https://hackforums.net/forumdisplay.php?fid=118)
+---- Thread: [Python] Simple code to understand in order to solve a hackerrank challenge (/showthread.php?tid=6276750)
Simple code to understand in order to solve a hackerrank challenge - Azythum - Aug 2, 2024
Hello hackforums coders,
I'm trying to solve a challenge on HackerRank. The challenge is more complex. But here is a small piece of code. I have the feeling that understanding this could allow me to understand more complex things.
Code
a = []
c = [0]
c[0]=1
a.append(c)
print(a)
c[0]=2
a.append(c)
print(a)
b=[]
b.append([1])
print(b)
b.append([2])
print(b)Here is the result in the console:
[[1]]
[[2], [2]]
[[1]]
[[1], [2]]
Normally, the two small pieces of code should produce the same outputs. But in one case, it gives me [[2], [2]], and in the other, it gives me [[1], [2]]. For me, [[1], [2]] is correct.
RE: Simple code to understand in order to solve a hackerrank challenge - Perlo - Aug 2, 2024
It might have something to do about the fact that when you append c to a, it actually creates a sort of link to the value of c. Where in the first case c[0] was set to 1. And this value was appended to a. Now in the next step we overwrite the value of c[0] to 2 and add it to a again. Now we might be able to refer to the list a, as: [c[0], c[0]]. Now because we changed c[0] to 2, it simply fills this last value in to the list of a, rather than putting in the values as copies of c[0].
RE: Simple code to understand in order to solve a hackerrank challenge - Azythum - Aug 2, 2024
(Aug 2, 2024 08:53 AM)Perlo Wrote: It might have something to do about the fact that when you append c to a, it actually creates a sort of link to the value of c. Where in the first case c[0] was set to 1. And this value was appended to a. Now in the next step we overwrite the value of c[0] to 2 and add it to a again. Now we might be able to refer to the list a, as: [c[0], c[0]]. Now because we changed c[0] to 2, it simply fills this last value in to the list of a, rather than putting in the values as copies of c[0].
Ok thanks very much for answering. I think i understand!
RE: Simple code to understand in order to solve a hackerrank challenge - Perlo - Aug 2, 2024
(Aug 2, 2024 09:24 AM)Azythum Wrote: Ok thanks very much for answering. I think i understand!
No problem! Glad to hear that it helped you out. If you need more assistance feel free to contact me.