[Interview type questions] MinQueue

Leetcode had a question about min stack, but there is no question about min queue. In this article, I wrote a simple one for min queue.

Solution:

 public static void main(String[] args) {
  MinQueue queue = new MinQueue();
  // Input 3 -> 1 -> 4 -> 2
  queue.offer(3).offer(1).offer(4).offer(2);
  //  0 0 0 1 1 1
  while(queue.isEmpty() == false) {
   System.out.println(queue.getMin());
   queue.poll();
  }
  // Output should be 1 -> 1 -> 2 -> 2
 }
 
 static class MinQueue {
  private Queue<Integer> mQueue = new LinkedList<>();
  private Deque<Integer> mMinDeque = new ArrayDeque<>();
  
  MinQueue offer(int val) {
   int min = val;
   while(!mMinDeque.isEmpty() && mMinDeque.getLast() > val) {
    mMinDeque.pollLast();
    min = val;
   }
   int size = mQueue.size() - mMinDeque.size();
   for (int i = 0; i <= size; i++) {
    mMinDeque.addLast(min);
   }
   mQueue.offer(val);
   return this;
  }
  
  int poll() {
   mMinDeque.poll();
   return mQueue.poll();
  }
  
  boolean isEmpty() {
   return mQueue.isEmpty();
  }
  
  int getMin() {
   return mMinDeque.peek();
  }
 }