Example: Merge Two Sorted Arrays (Two-Pointer) in C++

// Merge Two Sorted Arrays (Two-Pointer)
#include <iostream>
#include <vector>
#include <algorithm> // Not strictly needed for this approach but good practice for vector ops

int main() {
    // Step 1: Define the two sorted input arrays
    std::vector<int> arr1 = {1, 3, 5, 7, 9};
    std::vector<int> arr2 = {2, 4, 6, 8, 10, 12};

    // Step 2: Calculate the size of the merged array and declare it
    int m = arr1.size();
    int n = arr2.size();
    std::vector<int> merged_arr(m + n);

    // Step 3: Initialize pointers for arr1, arr2, and merged_arr
    int i = 0; // Pointer for arr1
    int j = 0; // Pointer for arr2
    int k = 0; // Pointer for merged_arr

    // Step 4: Merge elements while both arrays have elements to compare
    while (i < m && j < n) {
        if (arr1[i] <= arr2[j]) {
            merged_arr[k] = arr1[i];
            i++;
        } else {
            merged_arr[k] = arr2[j];
            j++;
        }
        k++;
    }

    // Step 5: Add remaining elements from arr1 (if any)
    while (i < m) {
        merged_arr[k] = arr1[i];
        i++;
        k++;
    }

    // Step 6: Add remaining elements from arr2 (if any)
    while (j < n) {
        merged_arr[k] = arr2[j];
        j++;
        k++;
    }

    // Step 7: Print the merged array
    std::cout << "Merged array using Two-Pointer Approach: ";
    for (int val : merged_arr) {
        std::cout << val << " ";
    }
    std::cout << std::endl;

    return 0;
}