MinStackUsingTwoStacks.java

packagecom.thealgorithms.stacks;

importjava.util.Stack;

/**
 * Min-Stack implementation that supports push, pop, and retrieving the minimum element in constant time.
 *
 * @author Hardvan
 */
publicfinalclassMinStackUsingTwoStacks {
MinStackUsingTwoStacks() {
 }

privatefinalStack<Integer> stack = newStack<>();
privatefinalStack<Integer> minStack = newStack<>();

/**
 * 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.
 */
publicvoidpush(intvalue) {
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}.
 */
publicvoidpop() {
if (stack.pop().equals(minStack.peek())) {
minStack.pop();
 }
 }

/**
 * Retrieves the top element of the stack.
 *
 * @return The top element.
 */
publicinttop() {
returnstack.peek();
 }

/**
 * Retrieves the minimum element in the stack.
 *
 * @return The minimum element.
 */
publicintgetMin() {
returnminStack.peek();
 }
}