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Author: shatakshigarg

MAX PRIORITY QUEUE.txt

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+import java.util.*;
+public class PQ {
+	// Complete this class
+    private ArrayList<Integer> heap;
+    
+    public PQ(){
+        heap = new ArrayList<>();
+    }
+	boolean isEmpty() {
+		if(heap.size()==0)
+        {
+            return true;
+        }
+        else
+        {
+            return false;
+        }
+	}
+
+	int getSize() {
+		return heap.size();
+	}
+
+	int getMax() {
+		if(isEmpty())
+        {
+            return Integer.MIN_VALUE;
+        }
+        return heap.get(0);
+	}
+
+	void insert(int element) {
+		heap.add(element);
+        
+        int childIndex = heap.size()-1;
+        int parentIndex = (childIndex-1)/2;
+        while(childIndex>0)
+        {
+            if(heap.get(childIndex)>heap.get(parentIndex))
+            {
+                int temp = heap.get(childIndex);
+                heap.set(childIndex,heap.get(parentIndex));
+                heap.set(parentIndex,temp);
+                childIndex=parentIndex;
+                parentIndex= (childIndex-1)/2;
+            }
+            else
+            {
+                return;
+            }
+        }
+	}
+
+	int removeMax() {
+		if(isEmpty())
+        {
+            return Integer.MIN_VALUE;
+        }
+        int ans = heap.get(0);
+        heap.set(0,heap.get(heap.size()-1));
+        heap.remove(heap.size()-1);
+        
+        int parentIndex = 0;
+        int leftIndex = 2*(parentIndex)+1;
+        int rightIndex = 2*(parentIndex)+2;
+        int maxIndex = parentIndex;
+        
+        while(leftIndex<heap.size())
+        {
+            if(heap.get(leftIndex)>heap.get(maxIndex))
+            {
+                maxIndex = leftIndex;
+            }
+            if(rightIndex<heap.size() && heap.get(rightIndex)> heap.get(maxIndex))
+            {
+                maxIndex = rightIndex;
+            }
+            if(maxIndex==parentIndex)
+            {
+                break;
+            }
+            int temp = heap.get(maxIndex);
+            heap.set(maxIndex,heap.get(parentIndex));
+            heap.set(parentIndex,temp);
+            parentIndex = maxIndex;
+            leftIndex = 2*(parentIndex)+1;
+            rightIndex = 2*(parentIndex)+2;
+            
+        }
+        return ans;
+	}
+}

REMOVE MIN.txt

@@ -0,0 +1,86 @@
+import java.util.ArrayList;
+
+class PriorityQueueException extends Exception {
+
+}
+
+public class PQ {
+
+    private ArrayList<Integer> heap;
+
+    public PQ() {
+        heap = new ArrayList<Integer>();
+    }
+
+    boolean isEmpty(){
+        return heap.size() == 0;
+    }
+
+    int size(){
+        return heap.size();
+    }
+
+    int getMin() throws PriorityQueueException{
+        if(isEmpty()){
+            // Throw an exception
+            throw new PriorityQueueException();
+        }
+        return heap.get(0);
+    }
+
+    void insert(int element){
+        heap.add(element);
+        int childIndex = heap.size() - 1;
+        int parentIndex = (childIndex - 1) / 2;
+
+        while(childIndex > 0){
+            if(heap.get(childIndex) < heap.get(parentIndex)){
+                int temp = heap.get(childIndex);
+                heap.set(childIndex, heap.get(parentIndex));
+                heap.set(parentIndex, temp);
+                childIndex = parentIndex;
+                parentIndex = (childIndex - 1) / 2;
+            }else{
+                return;
+            }
+        }
+    }
+
+
+ int removeMin() throws PriorityQueueException{
+		if(isEmpty()){
+			// Throw an exception
+			throw new PriorityQueueException();
+		}
+		int temp = heap.get(0);
+		heap.set(0, heap.get(heap.size() - 1));
+		heap.remove(heap.size() - 1);
+		int parentindex = 0;
+		int minIndex = parentindex;
+		int leftChildIndex = 1;
+		int rightChildIndex = 2;
+
+		while(leftChildIndex < heap.size()){
+
+			if(heap.get(leftChildIndex) < heap.get(minIndex)){
+				minIndex = leftChildIndex;
+			}
+			if(rightChildIndex < heap.size() && heap.get(rightChildIndex) < heap.get(minIndex)){
+				minIndex = rightChildIndex;
+			}
+			if(minIndex == parentindex){
+				break;
+			}else{
+				int temp1 = heap.get(parentindex);
+				heap.set(parentindex, heap.get(minIndex));
+				heap.set(minIndex, temp1);
+				parentindex = minIndex;
+				leftChildIndex = 2 * parentindex + 1;
+				rightChildIndex = 2 * parentindex + 2;
+			}
+		}
+		return temp;
+
+	}
+
+}