package com.thealgorithms.stacks;
import java.util.Stack;
/**
* Min-Stack implementation that supports push, pop, and retrieving the minimum element in constant time.
*
* @author Hardvan
*/
public final class MinStackUsingTwoStacks {
MinStackUsingTwoStacks() {
}
private final Stack<Integer> stack = new Stack<>();
private final Stack<Integer> minStack = new Stack<>();
/**
* Pushes a new element onto the {@code stack}.
* If the value is less than or equal to the current minimum, it is also pushed onto the {@code minStack}.
*
* @param value The value to be pushed.
*/
public void push(int value) {
stack.push(value);
if (minStack.isEmpty() || value <= minStack.peek()) {
minStack.push(value);
}
}
/**
* Removes the top element from the stack.
* If the element is the minimum element, it is also removed from the {@code minStack}.
*/
public void pop() {
if (stack.pop().equals(minStack.peek())) {
minStack.pop();
}
}
/**
* Retrieves the top element of the stack.
*
* @return The top element.
*/
public int top() {
return stack.peek();
}
/**
* Retrieves the minimum element in the stack.
*
* @return The minimum element.
*/
public int getMin() {
return minStack.peek();
}
}