Add 480_Sliding_Window_Median.java

Author: Sean Prashad

Two Heaps/480_Sliding_Window_Median.java

@@ -0,0 +1,53 @@
+class Solution {
+ public double[] medianSlidingWindow(int[] nums, int k) {
+ if (nums == null || nums.length == 0) {
+ return new double[] {};
+ }
+
+ MedianQueue mq = new MedianQueue();
+ double[] result = new double[nums.length - k + 1];
+ int idx = 0;
+
+ for (int i = 0; i < nums.length; i++) {
+ mq.offer(nums[i]);
+
+ if (mq.size() == k) {
+ result[idx++] = mq.getMedian();
+ mq.remove(nums[i + 1 - k]);
+ }
+ }
+
+ return result;
+ }
+
+ class MedianQueue {
+ private PriorityQueue<Integer> maxHeap;
+ private PriorityQueue<Integer> minHeap;
+
+ public MedianQueue() {
+ maxHeap = new PriorityQueue<>();
+ minHeap = new PriorityQueue<>(Collections.reverseOrder());
+ }
+
+ public void offer(int num) {
+ maxHeap.offer(num);
+ minHeap.offer(maxHeap.poll());
+
+ if (maxHeap.size() < minHeap.size()) {
+ maxHeap.offer(minHeap.poll());
+ }
+ }
+
+ public boolean remove(int num) {
+ return maxHeap.remove(num) || minHeap.remove(num);
+ }
+
+ public int size() {
+ return maxHeap.size() + minHeap.size();
+ }
+
+ public double getMedian() {
+ return maxHeap.size() > minHeap.size() ? maxHeap.peek() : ((long) maxHeap.peek() + minHeap.peek()) / 2.0;
+ }
+ }
+}