堆排序的 C++ 程序

堆排序是一种基于二叉堆数据结构的比较排序技术。它类似于我们首先找到最大元素并将最大元素放在最后的选择排序。我们对剩余元素重复相同的过程。

// C++ program for implementation of Heap Sort
#include 
using namespace std;
  
// To heapify a subtree rooted with node i which is
// an index in arr[]. n is size of heap
void heapify(int arr[], int n, int i)
{
    int largest = i; // Initialize largest as root
    int l = 2 * i + 1; // left = 2*i + 1
    int r = 2 * i + 2; // right = 2*i + 2
  
    // If left child is larger than root
    if (l < n && arr[l] > arr[largest])
        largest = l;
  
    // If right child is larger than largest so far
    if (r < n && arr[r] > arr[largest])
        largest = r;
  
    // If largest is not root
    if (largest != i) {
        swap(arr[i], arr[largest]);
  
        // Recursively heapify the affected sub-tree
        heapify(arr, n, largest);
    }
}
  
// main function to do heap sort
void heapSort(int arr[], int n)
{
    // Build heap (rearrange array)
    for (int i = n / 2 - 1; i >= 0; i--)
        heapify(arr, n, i);
  
    // One by one extract an element from heap
    for (int i = n - 1; i >= 0; i--) {
        // Move current root to end
        swap(arr[0], arr[i]);
  
        // call max heapify on the reduced heap
        heapify(arr, i, 0);
    }
}
  
/* A utility function to print array of size n */
void printArray(int arr[], int n)
{
    for (int i = 0; i < n; ++i)
        cout << arr[i] << " ";
    cout << "\n";
}
  
// Driver program
int main()
{
    int arr[] = { 12, 11, 13, 5, 6, 7 };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    heapSort(arr, n);
  
    cout << "Sorted array is \n";
    printArray(arr, n);
}

输出：

Sorted array is 
5 6 7 11 12 13

有关更多详细信息，请参阅有关堆排序的完整文章！

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