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HeapSort.java
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HeapSort.java
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public class HeapSort {
public static void sort(int arr[])
{
int N = arr.length;
// Build heap
for (int i = N / 2 - 1; i >= 0; i--)
heapify(arr, N, i);
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);
}
}
public static void heapify(int arr[], int N, int i)
{
int largest = i;
int l = 2 * i + 1;
int r = 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);
}
}
public static void main(String args[])
{
int n = 50;
int[] arr = new int[n];
for(int i=0;i<n;i++){
arr[i]=n-i;
}
long t1=System.nanoTime();
sort(arr);
long t2=System.nanoTime();
System.out.println("input : "+n+" running time : "+(t2-t1));
}
}