Merge pull request neetcode-gh#163 from r1cky0/patch-9

Create 295-Find-Median-from-Data-Stream.java

Author: neetcode-gh

java/295-Find-Median-from-Data-Stream.java

@@ -0,0 +1,36 @@
+class MedianFinder {
+    private Queue<Integer> smallHeap; //small elements - maxHeap
+    private Queue<Integer> largeHeap; //large elements - minHeap
+    
+    public MedianFinder() {
+        smallHeap = new PriorityQueue<>((a, b) -> b - a);
+        largeHeap = new PriorityQueue<>((a, b) -> a - b);
+    }
+    
+    public void addNum(int num) {
+        smallHeap.add(num);
+        if (smallHeap.size() - largeHeap.size() > 1 || !largeHeap.isEmpty() && smallHeap.peek() > largeHeap.peek()) {
+            largeHeap.add(smallHeap.poll());
+        }
+        if (largeHeap.size() - smallHeap.size() > 1) {
+            smallHeap.add(largeHeap.poll());
+        }
+    }
+    
+    public double findMedian() {
+        if (smallHeap.size() == largeHeap.size()) {
+            return (double)(largeHeap.peek() + smallHeap.peek()) / 2;
+        } else if (smallHeap.size() > largeHeap.size()) {
+            return (double)smallHeap.peek();
+        } else {
+            return (double)largeHeap.peek();
+        }
+    }
+}
+
+/**
+ * Your MedianFinder object will be instantiated and called as such:
+ * MedianFinder obj = new MedianFinder();
+ * obj.addNum(num);
+ * double param_2 = obj.findMedian();
+ */