class Solution:
    def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:

        ans_hashtable = {}
        stack = []

        for num in nums2:
            while stack and stack[-1] < num: # new is greater
                ans_hashtable[stack[-1]] = num # last number's answer = this num
                del stack[-1]            
            stack.append(num)

        for rest_element in stack:
            ans_hashtable[rest_element] = -1

        return [ans_hashtable[num] for num in nums1]