堆排序的Java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。

Java

// Java program for implementation of Heap Sort
public class HeapSort
{
    public void sort(int arr[])
    {
        int n = arr.length;
  
        // 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
            int temp = arr[0];
            arr[0] = arr[i];
            arr[i] = temp;
  
            // call max heapify on the reduced heap
            heapify(arr, i, 0);
        }
    }
  
    // 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)
        {
            int swap = arr[i];
            arr[i] = arr[largest];
            arr[largest] = swap;
  
            // Recursively heapify the affected sub-tree
            heapify(arr, n, largest);
        }
    }
  
    /* A utility function to print array of size n */
    static void printArray(int arr[])
    {
        int n = arr.length;
        for (int i=0; i

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