Reverse an array using Stack

Try it on GfG Practice

Given an array arr[] of size n, the task is to reverse the array using Stack.

Examples:

Input: arr = [10, 20, 30, 40, 50] 
Output: 50 40 30 20 10 
Explanation: Upon reversing the array becomes [50, 40, 30, 20, 10]. Therefore, the output is 50 40 30 20 10.

Input: arr = [ 1 ]
Output: 1
Explanation: Reversing the array does not changes the array as it only has a single element

Also read: Array Reverse – Complete Tutorial

The idea is to push all elements of the array into the stack. Since a stack follows the Last In, First Out (LIFO) principle, popping elements from the stack and storing them back into the array results in a reversed order. This efficiently reverses the array without using extra loops for swapping.

Follow the steps given below to reverse an array using stack. 

• Create an empty stack.
• One by one push all elements of the array to stack.
• One by one pop all elements from the stack and push them back to the array.

#include <bits/stdc++.h>
using namespace std;

void reverseArray(vector<int> &arr)
{
    int n = arr.size();
    //declare a stack
    stack<int> st;

    // push all elements of array into stack
    for (int i = 0; i < n; i++)
    {
        st.push(arr[i]);
    }
    
    int i = 0;
    // update the elements of the array
    while (!st.empty())
    {
        int top = st.top();
        st.pop();
        arr[i] = top;
        i++;
    }
    return;
}


int main()
{
    vector<int> arr = {100, 200, 300, 400};
    reverseArray(arr);
    for (auto it : arr)
        cout << it << " ";
    return 0;
}

import java.util.*;
class GfG {
    static void reverseArray(int arr[])
    {
        int n = arr.length;
        //declare a stack
        Stack<Integer> st = new Stack<>();
        
        //push array elements into stack
        for (int i = 0; i < n; i++) {
            st.push(arr[i]);
        }
        
        // update elements of array 
        int i = 0;
        while (st.empty() == false) {
            int top = st.peek();
            st.pop();
            arr[i] = top;
            i++;
        }
        return;
    }

    public static void main(String args[])
    {
        int[] a = new int[] { 100, 200, 300, 400 };

        reverseArray(a);
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }
    }
}

def reverseArray(arr):
    n = len(arr)
    st = []  

    # push all elements of array into stack
    for i in range(n):
        st.append(arr[i])
        
    # update the elements of array
    i = 0
    while(len(st) > 0):
        top = st.pop()
        arr[i] = top
        i += 1

    


n = 4

arr = [100, 200, 300, 400]

reverseArray(arr)
for i in range(n):
        print(arr[i], end=" ")

using System;
using System.Collections.Generic;
class GfG {
    public static void reverseArray(int[] arr)
    {
        int n = arr.Length;
        Stack<int> st = new Stack<int>();
        
        // pushing array elements into stack
        for (int i = 0; i < n; i++) {
            st.Push(arr[i]);
        }

        // Reverse the array elements
        for (int i = 0; i < n; i++) {
            int top = st.Peek();
            st.Pop();
            arr[i] = top;
        }
        return;
    }

    public static void Main()
    {
        int n = 4;
        int[] a = new int[] { 100, 200, 300, 400 };
        reverseArray(a);
        for (int i = 0; i < n; i++) {
            Console.Write(a[i] + " ");
        }
    }
}

function reverseArray(arr)
{
    let n = arr.length;
    // Declare a stack
    const st = []; 

    // push all elements of array into stack
    for (let i = 0; i < n; i++) {
        st.push(arr[i]);
    }
    let i = 0;

    //updating elements of array
    while (st.length) {

        // get top element of stack and pop it
        const top = st.pop();

        // update ith index of array and move to next index
        arr[i] = top;
        i++;
    }

    return;
}

const n = 4;

const arr = [ 100, 200, 300, 400 ];

reverseArray(arr);
console.log(arr.join(" "))

400 300 200 100