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70 lines (56 loc) · 1.94 KB
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// Java Program to implement Heap Sort
public class HeapSort {
// Function to heapify a subtree rooted with node i (index) in array of size n
void heapify(int arr[], int n, int i) {
int largest = i; // Initialize largest as root
int left = 2 * i + 1; // Left child
int right = 2 * i + 2; // Right child
// If left child is larger than root
if (left < n && arr[left] > arr[largest])
largest = left;
// If right child is larger than largest so far
if (right < n && arr[right] > arr[largest])
largest = right;
// If largest is not root
if (largest != i) {
int temp = arr[i];
arr[i] = arr[largest];
arr[largest] = temp;
// Recursively heapify the affected subtree
heapify(arr, n, largest);
}
}
// Main function to perform heap sort
void heapSort(int arr[]) {
int n = arr.length;
// Step 1: Build max heap
for (int i = n / 2 - 1; i >= 0; i--)
heapify(arr, n, i);
// Step 2: Extract elements from heap one by one
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 heapify on the reduced heap
heapify(arr, i, 0);
}
}
// Utility function to print array
void printArray(int arr[]) {
for (int value : arr)
System.out.print(value + " ");
System.out.println();
}
// Driver code
public static void main(String args[]) {
int arr[] = {12, 11, 13, 5, 6, 7};
System.out.println("Original array:");
for (int x : arr)
System.out.print(x + " ");
HeapSort hs = new HeapSort();
hs.heapSort(arr);
System.out.println("\n\nSorted array using Heap Sort:");
hs.printArray(arr);
}
}