HeapSort

heapSort.cpp

@@ -0,0 +1,115 @@
+#include<iostream>
+#include<cmath>
+
+using namespace std;
+
+int find_min_element_index(int a[] , int element , int left_child , int right_child){
+	if(a[element] <= a[left_child] && a[element] <= a[right_child])
+		return element;
+
+	if(a[left_child] <= a[element] && a[left_child] <= a[right_child])
+		return left_child;
+
+	if(a[right_child] <= a[element] && a[right_child] <= a[left_child])
+		return right_child;
+}
+
+int check_heap(int a[] , int n){
+
+	int second_last_level = (int)log2(n);
+
+	int check_elements_upto_index = pow( 2 , second_last_level+1)-2;
+	for(int i=0; i<=check_elements_upto_index; i++){
+
+		if(2*i+1 <= n-1 || 2*i+2 <= n-1){
+				if(2*i+1 <= n-1 && 2*i+2 <= n-1){
+					if(a[i] <= a[2*i+1] && a[i] <= a[2*i+2])
+					 	continue;
+					else
+						return 0;
+				}
+				else if(2*i+1 <= n-1){
+						if(a[i] <= a[2*i+1])
+							continue;
+						else
+							return 0;
+				}
+				else{
+						if(a[i] <= a[2*i+2])
+							continue;
+						else
+							return 0;
+				}
+			}
+			else{
+			   break;
+			}
+	}
+	return 1;
+}
+
+void heapify(int a[] , int n){
+	int heap_flag = 0;
+	while(heap_flag == 0){
+		int level = (int)log2(n);
+		int ending_index_at_corresponding_level = pow(2 ,level+1)-2;
+		for(int i = ending_index_at_corresponding_level;i >= 0 ;i--){
+					if(2*i+1 <= n-1 || 2*i+2 <= n-1){
+						if(2*i+1 <= n-1 && 2*i+2 <= n-1){
+				                    int min_index = find_min_element_index(a , i , 2*i+1 , 2*i+2);
+							 		if(min_index == i){
+							 			continue;
+									}
+									else{
+										int temp = a[min_index];
+										a[min_index] = a[i];
+										a[i] = temp;
+									}
+						}
+						else if( 2*i+1 <= n-1){
+								if(a[i] <= a[2*i+1])
+									continue;
+								else{
+										int temp = a[i];
+										a[i] = a[2*i+1];
+										a[2*i+1] = temp;
+									}
+						}
+						else{
+								if(a[i] <= a[2*i+2])
+									continue;
+								else{
+										int temp = a[i];
+										a[i] = a[2*i+2];
+										a[2*i+2] = temp;
+								}
+						}
+					}
+		}
+
+		heap_flag = check_heap(a , n);
+		if(heap_flag == 1){
+			cout << a[0] <<", ";
+			int temp = a[0];
+			a[0] = a[n-1];
+			a[n-1] = temp;
+			n = n-1;
+		}
+		if(n==1){
+			cout <<a[0] <<", ";
+			break;
+		}
+
+		heap_flag = check_heap(a , n);
+	}
+}
+
+
+int main(){
+	int list[] = {6,8,7,9,1,4,3,2,5,0};
+	cout<<endl<<"List of Elements before sort: ";
+	for(int i = 0; i<10; i++)
+        cout<<list[i]<<", ";
+	cout <<endl<<endl<<"Sorted Output as Follows : ";
+	heapify(list , 10);
+	cout<<endl;