CODEWITHSUNDEEP
python-3.x
yukta
yukta

Reputation: 1

my python left rotation array code is running okay in IDE by not on HackerRank platform

I tried to left rotate the array in python by giving the number of rotation I wanted but I'am unable to find the mistake in it It's perfectly working when I'm trying on jupyter IDE but HackerRank platform is showing wrong answer my code:

def rotateLeft(d, arr):
    for i in range(d):
        temp=arr[0]
        for j in range(len(arr)-1):
            arr[i]=arr[i+1]
        arr[len(arr)-1]=temp    
    return arr

The question
For example

input:
5 4
1 2 3 4 5

my output:
2 3 4 2 2

which is wrong. Where is the error?

Upvotes: 0

Views: 306

Answers (2)

Jan Kislinger
Jan Kislinger

Reputation: 1573

The update in the inner loop should use j instead of i. This should work

def rotateLeft(d, arr):
    for i in range(d):
        temp=arr[0]
        for j in range(len(arr)-1):
            arr[j]=arr[j+1]
        arr[len(arr)-1]=temp    
    return arr

However, there are simpler solutions to the question. For example the previous answer here.

Upvotes: 0

Jhoubert Rincon
Jhoubert Rincon

Reputation: 160

The solution is easier than you think, have you tried just cuting the array in two parts and concatenate inverting parts again.?

ex> [1,2,3,4] 2 rotate: [3,4] + [1,2]

result : 3,4,1,2

In python is so easy to do this.

def rotateLeft(d, arr):
    return arr[d:] + arr[0:d]

This solution have a bug, when the number of rotations are greater than length of the array wont do nothing, so if you calculate the mod of d you can pass it any number.

def rotateLeft(d, arr):
    d = d % len(arr)
    return arr[d:] + arr[0:d]

Upvotes: 1

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