Reversing a Stack with the help of another empty Stack

Given a Stack consisting of N elements, the task is to reverse the Stack using an extra stack.

Examples:

Input: stack = {1, 2, 3, 4, 5} 
Output:
1 
2 
3 
4 
5 
Explanation:
Input Stack: 
5 
4 
3 
2 
1 
Reversed Stack: 
1 
2 
3 
4 
5

Input: stack = {1, 3, 5, 4, 2} 
Output:
1 
3 
5 
4 
2

Approach 1: Follow the steps below to solve the problem:

• Initialize an empty stack.
• Pop the top element of the given stack S and store it in a temporary variable.
• Transfer all the elements of the given stack to the stack initialized above.
• Push the temporary variable into the original stack.
• Transfer all the elements present in the new stack into the original stack.

Below is the implementation of the above approach.

1 2 3 4 5

Time Complexity: O(N²) 
Auxiliary Space: O(N)

Approach 2: Follow the steps below to solve the problem:

• Initialize an empty stack called ans.
• Pop the top element of the given stack S and push it into the stack ans.
• Return the stack ans, which will contain the reversed elements of the stack S.

Below is the implementation of the above approach.

1 2 3 4 5 

Time Complexity: O(N) 
Auxiliary Space: O(N)