Example: Median of Two Sorted Arrays - Merge and Find in Java

// Median of Two Sorted Arrays - Merge and Find
import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        // Example 1
        int[] nums1_ex1 = {1, 3};
        int[] nums2_ex1 = {2};
        System.out.println("Input: nums1=" + Arrays.toString(nums1_ex1) + ", nums2=" + Arrays.toString(nums2_ex1));
        System.out.println("Median (Merge and Find): " + findMedianSortedArraysMerge(nums1_ex1, nums2_ex1)); // Expected: 2.0

        // Example 2
        int[] nums1_ex2 = {1, 2};
        int[] nums2_ex2 = {3, 4};
        System.out.println("Input: nums1=" + Arrays.toString(nums1_ex2) + ", nums2=" + Arrays.toString(nums2_ex2));
        System.out.println("Median (Merge and Find): " + findMedianSortedArraysMerge(nums1_ex2, nums2_ex2)); // Expected: 2.5
    }

    public static double findMedianSortedArraysMerge(int[] nums1, int[] nums2) {
        // Step 1: Determine the total length of the combined arrays
        int m = nums1.length;
        int n = nums2.length;
        int totalLength = m + n;

        // Step 2: Create a new array to store the merged elements
        int[] merged = new int[totalLength];
        int i = 0, j = 0, k = 0; // Pointers for nums1, nums2, and merged array

        // Step 3: Merge nums1 and nums2 into 'merged' while maintaining sorted order
        while (i < m && j < n) {
            if (nums1[i] <= nums2[j]) {
                merged[k++] = nums1[i++];
            } else {
                merged[k++] = nums2[j++];
            }
        }

        // Step 4: Copy remaining elements from nums1, if any
        while (i < m) {
            merged[k++] = nums1[i++];
        }

        // Step 5: Copy remaining elements from nums2, if any
        while (j < n) {
            merged[k++] = nums2[j++];
        }

        // Step 6: Calculate the median from the merged array
        if (totalLength % 2 == 1) {
            // Odd length: median is the middle element
            return (double) merged[totalLength / 2];
        } else {
            // Even length: median is the average of the two middle elements
            int mid1 = merged[totalLength / 2 - 1];
            int mid2 = merged[totalLength / 2];
            return (double) (mid1 + mid2) / 2.0;
        }
    }
}