What is the mistake in my code

Question

Reverse an array

First line of input contains N-size of array and second line contains elements of array

Input format
5
1 8 4 3 9

Output
9 3 4 8 1

My code :
def rev(arr,start,end):
while start < end:
arr[start],arr[end]=arr[end],arr[start]
start+=1
end-=1

n= int(input())
arr = list(map(int,input().split()))

rev(arr,0,4)
print(arr)

I don't want []'s in the output what corrections must be done?

Answer 1

DavX

there is an input taken and stored in variable *n*. this variable is never used !?

Answer 2

Y Harshitha

> since there are 2 inputs required (1st: number of elements to input, 2nd: elements), i suppose the input has to be done in a loop.

nums_lst = []
count = int(input())
while count > 0:
nums_lst.insert(0, int(input()))
count -= 1
print(*nums_lst)

Answer 3

Thank you

Answer 4

If you need reason, then read about Tuple unpacking.. Or this thread may help you..
Your welcome...
https://www.sololearn.com/Discuss/2521834/?ref=app

Answer 5

print( *arr)

Answer 6

… Y Harshitha,

Also notice you have the start/end params of your function call as literals - you won’t be able to run:
3
1 2 3

Using your input here’s a shorter method:

n = int(input())
arr = list(map(int,input().split()))

print(*arr[::-1])

Answer 7

DavX Jayakrishna 🇮🇳 thanks learned new concepts 😊

Answer 8

Lothar,

Haha indeed n isn’t used, that was to demonstrate another method of reversing ( [::-1] ) - it did state ‘using your input’, else the tests would fail.

A suggestion was also made ref using literals in their function call.

rev(arr, 0, n-1) - for example would have worked with their own attempt 👍😁

p.s your example doesn’t work with the input format, as the second input is provided in one line seperated by whitespace.