Example: Even-Odd Sort using Auxiliary Array in C

// Even-Odd Sort using Auxiliary Array
#include <stdio.h>
#include <stdlib.h> // For malloc and free

void evenOddSortAuxiliary(int arr[], int n) {
    // Step 1: Allocate memory for a temporary array
    int *temp_arr = (int *)malloc(n * sizeof(int));
    if (temp_arr == NULL) {
        printf("Memory allocation failed!\n");
        return;
    }

    int k = 0; // Index for the temporary array

    // Step 2: Copy all even numbers to the temporary array
    for (int i = 0; i < n; i++) {
        if (arr[i] % 2 == 0) {
            temp_arr[k++] = arr[i];
        }
    }

    // Step 3: Copy all odd numbers to the temporary array
    for (int i = 0; i < n; i++) {
        if (arr[i] % 2 != 0) {
            temp_arr[k++] = arr[i];
        }
    }

    // Step 4: Copy elements back from temporary array to original array
    for (int i = 0; i < n; i++) {
        arr[i] = temp_arr[i];
    }

    // Step 5: Free the allocated memory
    free(temp_arr);
}

void printArray(int arr[], int n) {
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

int main() {
    int arr[] = {12, 34, 45, 9, 8, 90, 3};
    int n = sizeof(arr) / sizeof(arr[0]);

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

    evenOddSortAuxiliary(arr, n);

    printf("Sorted array (Auxiliary Array): ");
    printArray(arr, n);

    int arr2[] = {7, 2, 10, 5, 1, 8, 4};
    n = sizeof(arr2) / sizeof(arr2[0]);

    printf("Original array: ");
    printArray(arr2, n);

    evenOddSortAuxiliary(arr2, n);

    printf("Sorted array (Auxiliary Array): ");
    printArray(arr2, n);

    return 0;
}