Solution 2: Min Stack

public class MinStack {
	private Stack<Integer> normal;
	private Stack<Integer> min;

	public MinStack() {
		normal = new Stack<Integer>();
		min = new Stack<Integer>();
	}

	public void push(int elem) {
		normal.push(elem);
		if (min.isEmpty() || min.peek() >= elem) {
			min.push(elem);
		}
	}

	public int pop() throws Exception {
		if (normal.isEmpty()) {
			throw new Exception("Error: The Stack is Empty!");
		}
		int res = normal.pop();
		if (min.peek() == res) {
			min.pop();
		}
		return res;
	}

	public int getMin() throws Exception {
		if (min.isEmpty()) {
			throw new Exception("Error: The Stack is Empty!");
		}
		return min.peek();
	}
}