MinStack.java

// Time Complexity : O(1) for all operations
// Space Complexity : O(n)
// Did this code successfully run on Leetcode : Yes
// Any problem you faced while coding this : No


// Your code here along with comments explaining your approach
// 1: Implementing this solution with one stack containing the item and one with the minimum value
// 2: All operations are performed on both stacks to maintain an accurate representation
// 3: After popping, the min is updated using the peek function

class MinStack {
    Stack<Integer> stack;
    Stack<Integer> minStack;
    int min;

    public MinStack() {
        this.stack = new Stack<>();
        this.minStack = new Stack<>();
        this.min = Integer.MAX_VALUE;
        this.minStack.push(min);
    }

    public void push(int val) {
        min = Math.min(min, val);
        stack.push(val);
        minStack.push(min);
    }

    public void pop() {
        stack.pop();
        minStack.pop();
        min = minStack.peek();
    }

    public int top() {
        return stack.peek();
    }

    public int getMin() {
        return min;
    }
}