Example: Merge Two Sorted Arrays (Two-Pointer Approach)

// Merge Two Sorted Arrays (Two-Pointer Approach)
#include <stdio.h>
#include <stdlib.h> // Required for malloc

void mergeSortedArrays(int arr1[], int n1, int arr2[], int n2, int mergedArr[]) {
    int i = 0; // Pointer for arr1
    int j = 0; // Pointer for arr2
    int k = 0; // Pointer for mergedArr

    // Step 1: Compare elements from both arrays and place the smaller one
    while (i < n1 && j < n2) {
        if (arr1[i] <= arr2[j]) {
            mergedArr[k++] = arr1[i++];
        } else {
            mergedArr[k++] = arr2[j++];
        }
    }

    // Step 2: Add remaining elements from arr1 (if any)
    while (i < n1) {
        mergedArr[k++] = arr1[i++];
    }

    // Step 3: Add remaining elements from arr2 (if any)
    while (j < n2) {
        mergedArr[k++] = arr2[j++];
    }
}

int main() {
    int arr1[] = {1, 3, 5, 7};
    int n1 = sizeof(arr1) / sizeof(arr1[0]);

    int arr2[] = {2, 4, 6, 8, 9};
    int n2 = sizeof(arr2) / sizeof(arr2[0]);

    int n_merged = n1 + n2;
    int *mergedArr = (int *)malloc(n_merged * sizeof(int)); // Dynamically allocate memory

    if (mergedArr == NULL) {
        printf("Memory allocation failed!\n");
        return 1;
    }

    // Step 4: Call the merge function
    mergeSortedArrays(arr1, n1, arr2, n2, mergedArr);

    // Step 5: Print the merged array
    printf("Merged array: ");
    for (int i = 0; i < n_merged; i++) {
        printf("%d ", mergedArr[i]);
    }
    printf("\n");

    free(mergedArr); // Free dynamically allocated memory
    return 0;
}