// This is an insertion-sort program, created using Google Gemini.

#include <stdio.h>

// --- Global Variables ---
// Array to be sorted
int input[5] = {8, 2, 5, 1, 4};
// Array to store the sorted result
int output[5];
// Length of the arrays
int array_length = 5;

// --- Helper Functions ---

/**
 * @brief Swaps two integer values using pointers.
 */
void swap(int* a, int* b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

/**
 * @brief Partitions the array for quicksort.
 * This implementation uses the Lomuto partition scheme,
 * choosing the last element as the pivot.
 *
 * @param arr The array to partition.
 * @param low The starting index of the partition.
 * @param high The ending index (and pivot index) of the partition.
 * @return The new index of the pivot after partitioning.
 */
int partition(int arr[], int low, int high) {
    // Choose the last element as the pivot
    int pivot = arr[high]; 
    
    // Index of the smaller element
    int i = (low - 1);

    // Iterate from the start (low) to just before the pivot (high - 1)
    for (int j = low; j <= high - 1; j++) {
        // If the current element is smaller than the pivot
        if (arr[j] < pivot) {
            i++; // Increment the index for the "smaller" section
            swap(&arr[i], &arr[j]); // Move this element to the "smaller" section
        }
    }
    
    // Place the pivot in its correct sorted position
    swap(&arr[i + 1], &arr[high]);
    return (i + 1); // Return the pivot's new index
}

// --- Quicksort Main Function ---

/**
 * @brief The main recursive quicksort function.
 *
 * @param arr The array to sort.
 * @param low The starting index of the section to sort.
 * @param high The ending index of the section to sort.
 */
void quickSort(int arr[], int low, int high) {
    if (low < high) {
        // Find the partitioning index 'pi'
        // arr[pi] is now in its correct sorted place
        int pi = partition(arr, low, high);

        // Recursively sort the elements before the partition
        quickSort(arr, low, pi - 1);
        
        // Recursively sort the elements after the partition
        quickSort(arr, pi + 1, high);
    }
}

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

// --- Main Program Execution ---

int main() {
    // Call quicksort on the global 'input' array
    // We pass 0 as the low index and (array_length - 1) as the high index
    quickSort(input, 0, array_length - 1);

    // Copy the now-sorted 'input' array into the 'output' array
    for (int i = 0; i < array_length; i++) {
        output[i] = input[i];
    }

    // Print the final 'output' array
    printf("Sorted output array: \n");
    printArray(output, array_length);

    return 0;
}