Merge pull request #38 from aaryahjolia/main

Heap Sort

All Other Program/Heap_Sort.cpp

@@ -0,0 +1,75 @@
+/*
+Heap Sort arranges an array in a binary tree, Make it a Max Heap and then store larger values from end to make a sorted array.
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+
+// heapify function to swap values to make a max heap binary tree (Tree in which the root element will be larger than child nodes).
+void heapify(int ar[],int n,int i){
+    int largest=i;
+    // Left and right child of tree when arranged as tree from array
+    int left=2*i+1;
+    int right=2*i+2;
+    if(ar[left]>ar[largest] && left<n){
+        largest=left;
+    }
+    if(ar[right]>ar[largest] && right<n){
+        largest=right;
+    }
+    // Swap elements if root is smaller and call heapify to make max heap tree
+    if(largest!=i){
+        swap(ar[i],ar[largest]);
+        heapify(ar,n,largest);
+    }
+}
+
+// Heap Sort Logic
+void heap_sort(int ar[],int n){
+    // Arranging array in a max heap binary tree format
+    for(int i=n/2;i>=0;--i){
+        heapify(ar,n,i);
+    }
+
+    // Swap 0th element to last element as 0th will be largest value according to max heap tree and run heapify again except on swapped element, Hence array will be sorted. 
+    for(int i=n-1;i>=0;--i){
+        swap(ar[0],ar[i]);
+        heapify(ar,i,0);
+    }
+}
+
+//Sorting Algorithm Boiler code to take input of array, call the sorting function and print the array.
+int main(){
+    cout<<"Enter size of array : ";
+    int size;
+    cin>>size;
+    int ar[size];
+    for(int i=0;i<size;i++){
+        cout<<"Enter element "<<(i+1)<<": ";
+        cin>>ar[i];
+    }    
+    cout<<"Before Sort : "<<endl;
+    for(int i=0;i<size;i++){
+        cout<<ar[i]<<" ";
+    }
+    cout<<endl;
+    heap_sort(ar,size);
+    cout<<"After sort : "<<endl;
+    for(int i=0;i<size;i++){
+        cout<<ar[i]<<" ";
+    }
+    cout<<endl;
+return 0;
+}
+
+/*
+## Run Code
+https://ide.geeksforgeeks.org/82b72ddc-f473-422d-b041-155c6f1d8fd1
+
+## Complexities
+### Time complexity   : 
+Best Case  : O(n)  
+Worst Case : O(n logn) 
+### Space complexity  : 
+O(1)
+*/