Create Median Priority Queue.java

Java/Median Priority Queue.java

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+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+  public static class MedianPriorityQueue {
+    PriorityQueue<Integer> left;
+    PriorityQueue<Integer> right;
+
+    public MedianPriorityQueue() {
+      left = new PriorityQueue<>(Collections.reverseOrder());
+      right = new PriorityQueue<>();
+    }
+
+    public void add(int val) {
+      // write your code here
+      if(right.size() >0 && val > right.peek()){
+          right.add(val);
+      }else{
+          left.add(val);
+      }
+      if(left.size() - right.size() ==2){
+          right.add(left.remove());
+      }else if(right.size() - left.size() == 2){
+          left.add(right.remove());
+      }
+
+    }
+
+    public int remove() {
+      // write your code here
+      if(this.size()==0){
+          System.out.println("Underflow");
+          return -1;
+      }else if(left.size() >= right.size()){
+          return left.remove();
+      }else{
+          return right.remove();
+      }
+
+    }
+
+    public int peek() {
+      // write your code here
+      if(this.size() ==0){
+          System.out.println("Underflow");
+          return -1;
+      }else if(left.size() >= right.size()){
+          return left.peek();
+      }else{
+          return right.peek();
+      }
+    }
+
+    public int size() {
+      // write your code here
+      return left.size() + right.size();
+    }
+  }
+
+  public static void main(String[] args) throws Exception {
+    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    MedianPriorityQueue qu = new MedianPriorityQueue();
+
+    String str = br.readLine();
+    while (str.equals("quit") == false) {
+      if (str.startsWith("add")) {
+        int val = Integer.parseInt(str.split(" ")[1]);
+        qu.add(val);
+      } else if (str.startsWith("remove")) {
+        int val = qu.remove();
+        if (val != -1) {
+          System.out.println(val);
+        }
+      } else if (str.startsWith("peek")) {
+        int val = qu.peek();
+        if (val != -1) {
+          System.out.println(val);
+        }
+      } else if (str.startsWith("size")) {
+        System.out.println(qu.size());
+      }
+      str = br.readLine();
+    }
+  }
+}