class Solution(object):    def nextGreaterElement(self, findNums, nums):        hm = {}        stk = []        for n in nums:            while len(stk)>0 and stk[-1] < n:                hm[stk[-1]] = n                stk.pop()            stk.append(n)                return list(map(lambda x: hm[x] if x in hm else -1, findNums))