(C언어) 힙 정렬(heap sort)

다음 코드는 C언어로 구현한 힙정렬 소스입니다.

#include <stdio.h>

// Function to swap two elements
void swap(int* a, int* b)
{
    int temp = *a;
    *a = *b;
    *b = temp;
}

// Heapify the subtree rooted at index 'root'
void heapify(int arr[], int size, int root)
{
    int largest = root;         // Initialize largest as root
    int left = 2 * root + 1;    // Left child
    int right = 2 * root + 2;   // Right child

    // If left child is larger than root
    if (left < size && arr[left] > arr[largest])
        largest = left;

    // If right child is larger than current largest
    if (right < size && arr[right] > arr[largest])
        largest = right;

    // If largest is not root
    if (largest != root) {
        swap(&arr[root], &arr[largest]);

        // Recursively heapify the affected sub-tree
        heapify(arr, size, largest);
    }
}

// Main function to perform Heap Sort
void heapSort(int arr[], int size)
{
    // Build heap (rearrange array)
    for (int i = size / 2 - 1; i >= 0; i--)
        heapify(arr, size, i);

    // Extract elements from the heap one by one
    for (int i = size - 1; i >= 0; i--) {
        // Move current root to end
        swap(&arr[0], &arr[i]);

        // Call heapify on the reduced heap
        heapify(arr, i, 0);
    }
}

// Function to print an array
void printArray(int arr[], int size)
{
    for (int i = 0; i < size; i++)
        printf("%d ", arr[i]);
    printf("\n");
}

// Test the heap sort algorithm
int main()
{
    int arr[] = { 12, 11, 13, 5, 6, 7 };
    int size = sizeof(arr) / sizeof(arr[0]);

    printf("Original array: ");
    printArray(arr, size);

    heapSort(arr, size);

    printf("Sorted array: ");
    printArray(arr, size);
    
    return 0;
}

힙정렬 heap sort