74 lines
1.8 KiB
Java
74 lines
1.8 KiB
Java
public class HeapSort
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{
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public void sort(int arr[])
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{
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int n = arr.length;
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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(arr, 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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int temp = arr[0];
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arr[0] = arr[i];
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arr[i] = temp;
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// call max heapify on the reduced heap
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heapify(arr, i, 0);
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}
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}
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// To heapify a subtree rooted with node i which is
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// an index in arr[]. n is size of heap
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void heapify(int arr[], 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; // left = 2*i + 1
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int r = 2*i + 2; // right = 2*i + 2
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// If left child is larger than root
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if (l < n && arr[l] > arr[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 && arr[r] > arr[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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int swap = arr[i];
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arr[i] = arr[largest];
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arr[largest] = swap;
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// Recursively heapify the affected sub-tree
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heapify(arr, n, largest);
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}
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}
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/* A utility function to print array of size n */
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static void printArray(int arr[])
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{
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int n = arr.length;
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for (int i=0; i<n; ++i)
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System.out.print(arr[i]+" ");
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System.out.println();
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}
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// Driver program
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public static void main(String args[])
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{
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int arr[] = {12, 11, 13, 5, 6, 7};
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int n = arr.length;
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HeapSort ob = new HeapSort();
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ob.sort(arr);
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System.out.println("Sorted array is");
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printArray(arr);
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}
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}
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