Design a stack to support push, pop, and retrieving the minimum?

Short answer: element in constant time public class MinStack {

Example code

private Stack<int> stack = new Stack<int>();
private Stack<int> minStack = new Stack<int>(); Follow on: public void Push(int x) { stack.Push(x); if (minStack.Count == 0 || x <= minStack.Peek()) minStack.Push(x); }
public void Pop() {
if (stack.Peek() == minStack.Peek()) minStack.Pop(); stack.Pop(); }
public int Top() {
return stack.Peek();
}
public int GetMin() {
return minStack.Peek();
}
} Explanation: Use two stacks: one normal stack, one for minimum values. When pushing a smaller or equal value, push it on minStack; when popping, pop minStack if needed.

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.