Merge Sorted Array

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

Example 1:Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3 Output: [1,2,2,3,5,6] Explanation: The arrays we are merging are [1,2,3] and [2,5,6]. The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1.

Example 2:Input: nums1 = [1], m = 1, nums2 = [], n = 0 Output: [1] Explanation: The arrays we are merging are [1] and []. The result of the merge is [1].

Example 3:Input: nums1 = [0], m = 0, nums2 = [1], n = 1 Output: [1] Explanation: The arrays we are merging are [] and [1]. The result of the merge is [1]. Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.

Constraints:

• nums1.length == m + n
• nums2.length == n
• 0 <= m, n <= 200
• 1 <= m + n <= 200
• -109 <= nums1[i], nums2[j] <= 109

Follow up: Can you come up with an algorithm that runs in O(m + n) time?

import java.util.ArrayList;
import java.util.Comparator;

public class MergeSortedArray {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        ArrayList<Integer> list = new ArrayList<>();
        for (int i = 0; i < m; i++) {
            list.add(nums1[i]);
        }

        for (int j = 0; j < n; j++) {
            list.add(nums2[j]);
        }
        list.sort(Comparator.naturalOrder());
        int index = 0;
        for (Integer i : list) {
            nums1[index++] = i;
        }
    }

    public static void main(String[] args) {
        MergeSortedArray obj = new MergeSortedArray();
        obj.merge(new int[]{1, 2, 3, 0, 0, 0}, 3, new int[]{2, 5, 6}, 3);

    }
}

import java.util.ArrayList;

import java.util.Comparator;

​

public class MergeSortedArray {

    public void merge(int[] nums1, int m, int[] nums2, int n) {

        ArrayList<Integer> list = new ArrayList<>();

        for (int i = 0; i < m; i++) {

            list.add(nums1[i]);

        }

​

        for (int j = 0; j < n; j++) {

            list.add(nums2[j]);

        }

        list.sort(Comparator.naturalOrder());

        int index = 0;

        for (Integer i : list) {

            nums1[index++] = i;

        }

    }

​

    public static void main(String[] args) {

        MergeSortedArray obj = new MergeSortedArray();

        obj.merge(new int[]{1, 2, 3, 0, 0, 0}, 3, new int[]{2, 5, 6}, 3);

​

    }

}

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