包含min操作的栈

MinStack.java

import java.util.ArrayDeque;
import java.util.Deque;

public class MinStack<T extends Comparable<T>> {

  private Deque<CustomElem<T>> mDeque = new ArrayDeque<>();
  private T mMinElem = null;

  public void push(T t) {
    CustomElem<T> elem = new CustomElem<>();
    elem.mValue = t;
    if (mMinElem == null) {
      mMinElem = t;
    }
    if (mMinElem.compareTo(t) <= 0) {
      elem.minElem = mMinElem;
    } else {
      elem.minElem = t;
      mMinElem = t;
    }
    mDeque.push(elem);
  }
  
  public T min(){
    CustomElem<T> elem = mDeque.getFirst();
    return elem.minElem;
  }
  
  public void pop(){
    mDeque.removeFirst();
  }
  
  class CustomElem<T> {
    T mValue;
    T minElem;
  }

}

MinStackTest.java

public class MinStackTest {
  
  public static void main(String[] args) {
    MinStack<Integer> myStack = new MinStack<>();
    myStack.push(4);
    myStack.push(3);
    myStack.push(5);
    myStack.push(1);
    System.out.println(myStack.min());
    myStack.pop();
    System.out.println(myStack.min());
  }

}