Given two numbers N1 and N2 represented by two stacks, such that their most significant digits are present at the bottom of the stack, the task is to calculate and return the sum of the two numbers in the form of a stack.

**Examples: **

Input:_ N1={5, 8, 7, 4}, N2={2, 1, 3} _

Output:_ {6, 0, 8, 7}_

Explanation:

Step 1: Popped element from N1(= 4) + Popped element from N2(= 3) = {7} and rem=0.

Step 2: Popped element from N1(= 7) + Popped element from N2(= 1) = {7, 8} and rem=0.

Step 3: Popped element from N1(= 8) + Popped element from N2(= 2) = {7, 8, 0} and rem=1.

Step 4: Popped element from N1(= 5) = {7, 8, 0, 6}

On reverse the stack, the desired arrangement {6,0,8,7} is obtained.

Input_: N1={6,4,9,5,7}, N2={213} _

Output:{6, 5, 0, 0, 5}

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The problem can be solved using the concept of Add two numbers represented by linked lists. Follow the below steps to solve the problem.

1. Create a new stack,** res** to store the sum of the two stacks.
2. Initialize variables** rem **and **sum **to store the carry generated and the sum of top elements respectively.
3. Keep popping the top elements of both the stacks and push the **sum % 10 **to res and update rem as sum/10.
4. Repeat the above step until the stacks are empty. If rem is greater than 0, insert rem into the stack.
5. Reverse the res stack so that the most significant digit present at the bottom of the res stack.

#data structures #mathematical #stack #big data