67 lines
1.5 KiB
C++
67 lines
1.5 KiB
C++
#include <iostream>
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using namespace std;
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void heapify(int a[], int n, int i);
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void heapSort(int a[], int n);
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// Driver code
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int main()
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{
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cout << "Enter the length of array" << endl;
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int n;
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cin >> n;
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int *a = new int(n);
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// Getting elements of array
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cout << "Enter the elements of array" << endl;
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for (int i = 0; i < n; i++)
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cin >> a[i];
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cout << "Original array:\n";
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for (int i = 0; i < n; i++)
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cout << a[i] << " ";
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heapSort(a, n);
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cout << "\nSorted array:\n";
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for (int i = 0; i < n; i++)
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cout << a[i] << " ";
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delete (a);
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return 0;
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}
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// To heapify a subtree rooted with node i which is an index in a[]
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void heapify(int a[], int n, int i)
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{
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int largest = i; // Initialize largest as root
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int l = 2 * i + 1;
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int r = 2 * i + 2;
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// If left child is larger than root
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if (l < n && a[l] > a[largest])
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largest = l;
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// If right child is larger than largest so far
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if (r < n && a[r] > a[largest])
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largest = r;
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// If largest is not root
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if (largest != i)
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{
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swap(a[i], a[largest]);
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// Recursively heapify the affected sub-tree
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heapify(a, n, largest);
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}
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}
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void heapSort(int a[], int n)
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{
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// Build heap (rearrange array)
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for (int i = n / 2 - 1; i >= 0; i--)
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heapify(a, n, i);
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// One by one extract an element from heap
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for (int i = n - 1; i > 0; i--)
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{
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// Move current root to end
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swap(a[0], a[i]);
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// call max heapify on the reduced heap
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heapify(a, i, 0);
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}
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}
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