Each row of nums1 and nums2 is [id, value]. Within each input, IDs are unique and appear in increasing order. Combine the two arrays into one array with a single row per ID. If an ID appears in both inputs, add its two values; otherwise keep its existing value. Return the rows in increasing ID order, including only IDs present in at least one input.
Example 1:
Input: nums1 = [[1,5],[4,2]]
nums2 = [[1,3],[2,7]]
Output: [[1,8],[2,7],[4,2]]Explanation: ID 1 appears in both inputs, so its value becomes 5 + 3 = 8. IDs 2 and 4 keep their values of 7 and 2. Return [[1,8],[2,7],[4,2]] in increasing ID order.
Example 2:
Input: nums1 = [[2,4]]
nums2 = [[5,6]]
Output: [[2,4],[5,6]]Explanation: The inputs have no shared IDs. Keep both rows and order them by ID, giving [[2,4],[5,6]].
Example 3:
Input: nums1 = [[3,1000]]
nums2 = [[3,1000]]
Output: [[3,2000]]Explanation: Both rows refer to ID 3. Their values add to 2000, so the result contains the single row [3,2000].
Constraints:
1 <= nums1.length, nums2.length <= 200- Every row contains exactly two integers,
[id, value]. 1 <= id, value <= 1000- IDs in each input are unique and strictly increasing.