Next Greater Element I

The **next greater element** of some element `x` in an array is the **first greater** element that is **to the right** of `x` in the same array. You are given two **distinct 0-indexed** integer arrays `nums1` and `nums2`, where `nums1` is a subset of `nums2`. For each `0 <= i < nums1.length`, find the index `j` such that `nums1[i] == nums2[j]` and determine the **next greater element** of `nums2[j]` in `nums2`. If there is no next greater element, then the answer for this query is `-1`. Return _an array _`ans`_ of length _`nums1.length`_ such that _`ans[i]`_ is the **next greater element** as described above._   **Example 1:** **Input:** nums1 = [4,1,2], nums2 = [1,3,4,2] **Output:** [-1,3,-1] **Explanation:** The next greater element for each value of nums1 is as follows: - 4 is underlined in nums2 = [1,3,4,2]. There is no next greater element, so the answer is -1. - 1 is underlined in nums2 = [1,3,4,2]. The next greater element is 3. - 2 is underlined in nums2 = [1,3,4,2]. There is no next greater element, so the answer is -1. ``` **Example 2:** **Input:** nums1 = [2,4], nums2 = [1,2,3,4] **Output:** [3,-1] **Explanation:** The next greater element for each value of nums1 is as follows: - 2 is underlined in nums2 = [1,2,3,4]. The next greater element is 3. - 4 is underlined in nums2 = [1,2,3,4]. There is no next greater element, so the answer is -1. ```   **Constraints:** - `1 <= nums1.length <= nums2.length <= 1000` - `0 <= nums1[i], nums2[i] <= 104` - All integers in `nums1` and `nums2` are **unique**. - All the integers of `nums1` also appear in `nums2`.   **Follow up:** Could you find an `O(nums1.length + nums2.length)` solution?