What is the optimal time complexity of solving Min Stack?

The optimized solution achieves a time complexity of O(n) by using sorting, mathematical shortcuts, or hash table lookups.

What is the auxiliary space complexity for Min Stack?

The space complexity is O(1) since we only use a minimal/constant amount of extra memory for tracking variables (or auxiliary space if dynamic structures are allocated).

What are the typical edge cases we must handle in Min Stack?

Key edge cases include empty collections, negative or large bounds causing integer overflow, arrays with only one element, or inputs where target criteria are not met.

How can we optimize the brute force approach for Min Stack?

Brute force methods often inspect all possible combinations. We optimize this by sorting the input list to enable binary search, or tracking processed items in a set to avoid redundant nested loop lookups.

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Min Stack

Learn how to solve the 'Min Stack' problem. This detailed resource details brute force and optimized approaches.

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Problem Statement

Easy

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

Implement the MinStack class:

- MinStack() initializes the stack object.

- push(val: int) pushes the element val onto the stack.

- pop() removes the element on the top of the stack.

- top() -> int gets the top element of the stack.

- getMin() -> int retrieves the minimum element in the stack.

You must implement a solution with O(1) time complexity for each function.

Constraints

•-2^31 <= val <= 2^31 - 1
•Methods pop, top, and getMin are always called on non-empty stacks
•At most 3 * 10^4 calls will be made to push, pop, top, and getMin

Examples

Example 1

Input

["MinStack", "push", "push", "push", "getMin", "pop", "top", "getMin"]
[[], [-2], [0], [-3], [], [], [], []]

Output

[None, None, None, None, -3, None, 0, -2]

Explanation

MinStack created. Push -2, 0, -3. getMin() returns -3. Pop removes -3. top() returns 0. getMin() returns -2.

Need a Hint?

Analyze the input constraints. Try sorting first (O(n log n)) or using a hash map/set to track seen elements in O(n) time.

Edge Cases to Watch

Empty list or null input variables
Single item lists/arrays
Extremely large input bounds causing integer or stack overflow

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