Add Median Of Running Array

Author: shrutisheoran

Misc/MedianOfRunningArray.java

@@ -0,0 +1,50 @@
+import java.util.Collections;
+import java.util.PriorityQueue;
+
+/**********************
+author: shrutisheoran
+***********************/ 
+
+public class MedianOfRunningArray {
+    private PriorityQueue<Integer> p1;
+    private PriorityQueue<Integer> p2;
+
+    //Constructor
+    public MedianOfRunningArray() {
+        this.p1 = new PriorityQueue<>(Collections.reverseOrder()); //Max Heap
+        this.p2 = new PriorityQueue<>(); //Min Heap
+    }
+
+    /* 
+        Inserting lower half of array to max Heap
+        and upper half to min heap
+    */
+    public void insert(Integer e) {
+        p2.add(e);
+        if(p2.size() - p1.size() > 1)
+            p1.add(p2.remove());
+    }
+
+    /*
+        Returns median at any given point
+    */
+    public Integer median() {
+        if(p1.size()==p2.size())
+            return (p1.peek() + p2.peek())/2;
+        return  p1.size()>p2.size() ? p1.peek() : p2.peek();
+    }
+
+    public static void main(String[] args) {
+        /*
+            Testing the median function
+        */
+
+        MedianOfRunningArray p = new MedianOfRunningArray();
+        int arr[] = {10, 7, 4, 9, 2, 3, 11, 17, 14};
+        for(int i = 0 ; i < 9 ; i++) {
+            p.insert(arr[i]);
+            System.out.print(p.median() + " ");
+        }
+    }
+
+}