|
| 1 | +#include <bits/stdc++.h> |
| 2 | +using namespace std; |
| 3 | + |
| 4 | +// To heapify a subtree rooted with node i |
| 5 | +// which is an index in arr[]. |
| 6 | +// n is size of heap |
| 7 | +void heapify(int arr[], int N, int i) |
| 8 | +{ |
| 9 | + |
| 10 | + // Initialize largest as root |
| 11 | + int largest = i; |
| 12 | + |
| 13 | + // left = 2*i + 1 |
| 14 | + int l = 2 * i + 1; |
| 15 | + |
| 16 | + // right = 2*i + 2 |
| 17 | + int r = 2 * i + 2; |
| 18 | + |
| 19 | + // If left child is larger than root |
| 20 | + if (l < N && arr[l] > arr[largest]) |
| 21 | + largest = l; |
| 22 | + |
| 23 | + // If right child is larger than largest |
| 24 | + // so far |
| 25 | + if (r < N && arr[r] > arr[largest]) |
| 26 | + largest = r; |
| 27 | + |
| 28 | + // If largest is not root |
| 29 | + if (largest != i) { |
| 30 | + swap(arr[i], arr[largest]); |
| 31 | + |
| 32 | + // Recursively heapify the affected |
| 33 | + // sub-tree |
| 34 | + heapify(arr, N, largest); |
| 35 | + } |
| 36 | +} |
| 37 | + |
| 38 | +// Main function to do heap sort |
| 39 | +void heapSort(int arr[], int N) |
| 40 | +{ |
| 41 | + |
| 42 | + // Build heap (rearrange array) |
| 43 | + for (int i = N / 2 - 1; i >= 0; i--) |
| 44 | + heapify(arr, N, i); |
| 45 | + |
| 46 | + // One by one extract an element |
| 47 | + // from heap |
| 48 | + for (int i = N - 1; i > 0; i--) { |
| 49 | + |
| 50 | + // Move current root to end |
| 51 | + swap(arr[0], arr[i]); |
| 52 | + |
| 53 | + // call max heapify on the reduced heap |
| 54 | + heapify(arr, i, 0); |
| 55 | + } |
| 56 | +} |
| 57 | + |
| 58 | +// A utility function to print array of size n |
| 59 | +void printArray(int arr[], int N) |
| 60 | +{ |
| 61 | + for (int i = 0; i < N; ++i) |
| 62 | + cout << arr[i] << " "; |
| 63 | + cout << "\n"; |
| 64 | +} |
| 65 | + |
| 66 | +// Driver's code |
| 67 | +int main() |
| 68 | +{ |
| 69 | + int arr[] = { 12, 11, 13, 5, 6, 7 }; |
| 70 | + int N = sizeof(arr) / sizeof(arr[0]); |
| 71 | + |
| 72 | + // Function call |
| 73 | + heapSort(arr, N); |
| 74 | + |
| 75 | + cout << "Sorted array is \n"; |
| 76 | + printArray(arr, N); |
| 77 | +} |
0 commit comments