class Solution:
    def replaceElements(self, arr: List[int]) -> List[int]:

        # max to the right
        max_seen_so_far = -1

        for i in range(len(arr)-1, -1, -1):
            # first store thay you will use later before getting overwritten
            temp = arr[i]

            # this should be the first step that you should right
            # because of you have already obtained the answer from
            # the previous steps and that is what it is
            arr[i] = max_seen_so_far

            # you are literally doing this for the next step
            max_seen_so_far = max(max_seen_so_far, temp)

        return arr