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Python Code for Reverse an Array

October 7, 2022

Reverse an Array using Python

Here, in this page we will discuss the program to reverse an array using python programming language. We will discuss different approaches to reverse the array in this page and compare the complexity of different approaches.

Different Approaches :

Method 1 : Using Swapping
Method 2 : Using Recursion
Method 3 : Using Python List slicing

Method 1 :

Take two variables say start = 0 and end= arr.len()-1
Run a loop till start < end
Swap arr[start] with arr[end]
Increment start and decrement end by 1
Print array

Example :

Let's array is arr[5] = [10, 20, 30, 40, 50] n = 5 i = 0, j = 4 As (0 is less than 4) swap(arr[0],arr[4]) arr[0]=50 and arr[4]=10, i++(i.,e i=1) and j--(i.e, j=3) Again (1 is less than 3) swap(arr[1],arr[3]) arr[1]=40 and arr[3]=20, i++(i.,e i=2) and j--(i.e, j=2) Now, i is not less than j (as i=2 and j=2) so loop gets terminate and original array get reversed.

Method 1 : Code in Python

Run def reverseList(A, start, end): while start < end: A[start], A[end] = A[end], A[start] start += 1 end -= 1 # Driver function to test above function A = [10, 20, 30, 40, 50] reverseList(A, 0, 4) print(A)

Output

[50, 40, 30, 20, 10] Related Pages

Find Second Smallest Element in an Array

Calculate the sum of elements in an array

Sort first half in ascending order and second half in descending

Sort the elements of an array

Finding the frequency of elements in an array

Method 2 :

Create a recursive function reverseList and pass array , start and end index of array.
Recursively call the function reverseList.

Method 2 : Code in Python

Run def reverseList(A, start, end): if start >= end: return A[start], A[end] = A[end], A[start] reverseList(A, start+1, end-1) # Driver function to test above function A = [10, 20, 30, 40, 50] reverseList(A, 0, 4) print(A)

Output

[50, 40, 30, 20, 10]

Method 3 :

In this method we reverse the array using list slicing

Method 3 : Code in Python

Run def reverseList(A): print( A[::-1]) # Driver function to test above function A = [10, 20, 30, 40, 50] reverseList(A)

Output

[50, 40, 30, 20, 10]

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12 comments on “Python Code for Reverse an Array”

Chirag
def printOrder(arr, n): arr.sort()

mid = n//2

s1 = arr[:mid]

s2 = arr[:mid:-1]

print(s1+s2)

# Driver code arr = [ 5, 4, 6, 2, 1, 3, 8, -1 ] n = len(arr) printOrder(arr, n)
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Manoj
arr= [10, 89, 9, 56, 4, 80, 8,2] arr.reverse() print(arr)
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Bharath
#reversing the array def rev(arr): for i in range(len(arr)//2): arr[i],arr[-i-1]=arr[-i-1],arr[i] return arr print(rev([2,3,4,5,5,6,0]))

The best solution, That I explored
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Rahul
a=[1,2,3,4,5] c=[] for i in range(1,len(a)+1): c.append(a[-i]) print(c)
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MANOJ
arr=[1,2,3,4,5] Print(arr[::-1])
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RADHIKA
arr = [10, 13, 17, 11, 34, 21] A=arr.reverse() print(arr)
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Anshul
l=[1,2,3,8,3,3,0,98765,222,222] a=[] for i in range(len(l),0,-1): c=l[i-1] a.append(c) print(a)
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Anirudh
n = int(int(input())) arr = [] sum = 0 for i in range(n): ele = int(input()) arr.append(ele) print(arr) print(“the reverse”,arr[::-1])
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44_Harsh
a = input(“enter your sentence : “) print(a[::-1]) #OUTPUT enter your sentence : gnirts rof si siht this is for string
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Ashish
a=list(map(int,input().split())) print(a[::-1])
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KIRA
THIS LOOKS BETTER : x = int(input(“Enter Total Elements : “)) y = []

for i in range(1, x+1): z = input(“Enter Element {} : “.format(i)) y.append(z)

print(“Array is : {}”.format(y)) print(“Reversed Array is : {}”.format(y[::-1]))
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