1299. Replace Elements with Greatest Element on Right Side

Python

class Solution:
    def replaceElements(self, arr: List[int]) -> List[int]:
        length = len(arr)
        if length == 1:
            return [-1]

        for i in range(0, length-1):
            arr[i] = max(arr[i+1:])

        arr[length-1] = -1

        return arr