Left Rotation | HackerRank | Python | Data structure | Array | Interview
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- Опубліковано 11 жов 2024
- This video is about HackerRank Left Rotation problem.
A left rotation operation on an array of size n shifts each of the array's elements 1 unit to the left. For example, if 2 left rotations are performed on array [1,2,3,4,5], then the array would become [3,4,5,1,2].
Given an array of n integers and a number, d, perform d left rotations on the array. Then print the updated array as a single line of space-separated integers.
Problem:www.hackerrank...
sample code: letstacle.com/...
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Hey Programmer/Learner, if you have any better solution feel free to post in comment section.
new_arr = a[(d%n) : ] + a[0:(d%n) ]
it works the same coz by adding n to d it has no effect on the remainder , we can directly use d%n.
nice video.
@@priyankachoudhary934 Thanks @Priyanka. Yes we can directly use d%n coz when you simplify (n+d)%n you will get d%n.
Keep Learning Keep Supporting :)
@@codingcart yess :)
arr = arr[d:] + arr[0:d] also works ! Thanks a lot sir❤️❤️🙏
I have never seen such nice explanation of problems!
beautiful and simple thinking and teaching :) thanks!
Best explanation for rotational array
great comeback, better is a[d:] + a[0:d]
OP
Wow man. The last trick was simply awesome
Great explanation
Well Explained briefly. Great video
Glad you liked it!
A very easy and simple solution that works is this:
for i in range(d):
a.append(a.pop(0))
return a
this is O(n² ) due to pop() in position 0 being a O(n) operation
waaoo such a great logic thank u sooo much sir
Good going👍
i have tried to make it simple...it is working..
list1 = [0] * len(arr)
for i in range(len(arr)):
list1[i - d] = arr[i]
return list1
sir this video is simply awesome but please tell me how you make this logic ? how i came to know that now i have to do (n+d)%n how u came across this logic and how to made it please tell us so we can do question from our own!! thanks and a very good explanation thank you
Glad u liked it!!
Sunny, it's all about practising.
As a beginner, First you have to apply Brute Force Algorithms and then after go for optimization and during this process try to print the value at each step and see how actually the things are going, here you will learn so many things like you may get few patterns which are repeating as you saw in this problem and many more things.
But the key part is practising and solving the problem by different different logic.
Try these 2 problem.
ttps://ua-cam.com/video/Ms85EsPu7nc/v-deo.html
ua-cam.com/video/kHcv1tGnF5Y/v-deo.html
Hope this helps :)
Coding Cart thanks a lot buddy ❤️ hope to see 1M on this channel soon 🔥
What is rstrip?? And why u r taking for _ ??
Also plz check out New Year Chaos(hackerrank-->practice-->interview preparation kit-->new year chaos)
sure
check this one ua-cam.com/video/VT-ChOqUsBM/v-deo.html
i think index=n-(k%n) and retturn index will pass all the test cases
Why can't we use range(d%n)? if d=n=10^5 then loop won't execute
Just try once from your end. You will get the solution yourself :)
what does it mean: a=a[1:]+a[0:1]? Can you explain me?
a[1:] will slice value from index 1 to last and a[0:1] will slice the value from 0th index to 1(excluded) i.e the very 1st value.
eg: a=[4,5,3,6,7]
a[1:] will give [5,3,6,7]
a[0:1] will give [4]
Hope this helps :)
How can I unpack using function? Since I have to end it with return statement I am unable to unpack it.
share your code please.
Plz make a vedio on perfection quotients problem (hackerrank-->compete-->project euler-->#241perfection quotients)..I don't know python☹️ can u plzz solve it in Java🙏🙏
Sure
I guess one thing is to also keep in mind, if the length of list equals the rotations, it will put back the list as is, so just returned it.
what can we do if they give in the form of recursion like
def rotLeft(a, d):
if __name__ == '__main__':
Looks like you can use a[d%n:] + a[0:d%n] and get the same result because (d+n)%n is the same as d%n.
Correct ..You can modify that i have written coz i was formulating the pattern 😊
@@codingcart Thank you very much for this video and your breakdown of the logic.
simply type -- return (arr[d:]+arr[:d])
Correct .But here i have formulated the logic step wise so that everyone can easily understand :)
@@codingcart nice sir, but I want to know how did you develop logic for each question, I just Python for 1 month and now I am hacker rank... Can you please tell how do I develop fast logic... How should I think for attempting the problem???
It's all about practice and solving alots of different different types of problem.
By the way you are on good track ..Keep going 😊
@@codingcart ok sir thanks
That's my code - It is passing all testcases except 2 testcases. Why Sir ?
def rotLeft(a, d):
for i in range(d):
a=a[1:]+a[0:1]
return a
Hi Sushrut,
We have explained this case in our 1st solution @11:22. If you see a=a[1:]+a[0:1] for this assignment ,in each iterartion we are performing slicing operation which made this solution to Terminate due to Time out. After this we came with better solution looking the output pattern. Please have a look you will understand easily :).
Try this problem ua-cam.com/video/XWG58qrcB50/v-deo.html, and hope you dont use slicing here :).
It printed the whole table instead of the last calculation
Hi Olga, the requirement was to rotate on the given number, so we have to rotate the list and print the whole list again after n rotation.
Yes, it rotated but it prints every step of rotation instead 1 last step
@@Santana_bold No..You can see the code in description section.
Can't we just write?
a[d:]+a[0:d]
return a
My code perfectly solved all the test cases with no tle
It's the same, I have just generalized the logic as per the explanation 😊
@@codingcart had you make a video on DFS and BFS topics?
On Monday my hackwithifny exam is scheduled if you can give me with some graph questions link ,that would be a great help.