Create MaxPriorityQueue.cpp

Author: Manvityagi

Data Structures/MaxPriorityQueue.cpp

@@ -0,0 +1,116 @@
+
+ 
+int main() {
+    PriorityQueue pq;
+    int choice;
+    cin >> choice;
+    while(choice != -1) {
+        switch(choice) {
+            case 1 : // insert
+                int element;
+                cin >> element;
+                pq.insert(element);
+                break;
+            case 2 : // getMax
+                cout << pq.getMax() << endl;
+                break;
+            case 3 : // removeMax
+                cout << pq.removeMax() << endl;
+                break;
+            case 4 : // size
+                cout << pq.getSize() << endl;
+                break;
+            case 5 : // isEmpty
+                if(pq.isEmpty()) {
+                    cout << "true" << endl;
+                }
+                else {
+                    cout << "false" << endl;
+                }
+            default :
+                return 0;
+        }
+        cin >> choice;
+    }
+}
+
+#include <vector>
+class PriorityQueue {
+    vector<int> pq;
+  public:
+  PriorityQueue(){
+    
+  }
+  int getSize(){
+    return pq.size();
+  }
+  
+   bool isEmpty() {
+        return pq.size() == 0;
+    }
+  
+    int getMax() {
+        if(isEmpty()) {
+            return 0;		// Priority Queue is empty
+        }
+        return pq[0];
+    }
+  
+ void insert(int element) {
+        pq.push_back(element);
+        
+        int childIndex = pq.size() - 1;
+        
+        while(childIndex > 0) {
+            int parentIndex = (childIndex - 1) / 2;
+            
+            if(pq[childIndex] > pq[parentIndex]) {
+                int temp = pq[childIndex];
+                pq[childIndex] = pq[parentIndex];
+                pq[parentIndex] = temp;
+            }
+            else {
+                break;
+            }
+            childIndex = parentIndex;
+        }
+        
+    }
+ 
+    
+    int removeMax() {
+      if(pq.size() == 0)
+        return 0;
+      int minindex;
+      int todel = pq[0];
+        pq[0] = pq[pq.size() - 1];
+        pq.pop_back();
+      
+      int parentindex  = 0;
+      int childindex1 = 1;
+      int childindex2 = 2;
+      while(childindex1 < pq.size()){
+      
+        if(pq[childindex1] > pq[parentindex] || pq[childindex2] > pq[parentindex]){
+         if(pq[childindex1] > pq[childindex2])
+            minindex = childindex1;
+          else
+            minindex = childindex2;
+          
+          int temp = pq[parentindex];
+          pq[parentindex] = pq[minindex];
+          pq[minindex] = temp;
+          
+          parentindex = minindex;
+          childindex1 = 2*parentindex + 1;
+          childindex2 = 2*parentindex + 2; 
+                                                     
+        }else
+          break;
+      }
+       return todel;
+    }
+    
+      
+   
+};