replace-elements-with-greatest-element-on-right-side_1299.py

# Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last element with -1.

# After doing so, return the array.


# Example 1:

# Input: arr = [17,18,5,4,6,1]
# Output: [18,6,6,6,1,-1]
# Explanation:
# - index 0 --> the greatest element to the right of index 0 is index 1 (18).
# - index 1 --> the greatest element to the right of index 1 is index 4 (6).
# - index 2 --> the greatest element to the right of index 2 is index 4 (6).
# - index 3 --> the greatest element to the right of index 3 is index 4 (6).
# - index 4 --> the greatest element to the right of index 4 is index 5 (1).
# - index 5 --> there are no elements to the right of index 5, so we put -1.
# Example 2:

# Input: arr = [400]
# Output: [-1]
# Explanation: There are no elements to the right of index 0.

# ---------------------------------------Runtime 590 ms Beats 79.18% Memory 18.4 MB Beats 9.14%---------------------------------------

from collections import deque
from typing import List, Deque


class Solution:
    def replaceElements(self, arr: List[int]) -> List[int]:
        d: Deque[int] = deque(arr)
        output: list[int] = []
        greatest_num: int = max(d)
        while d:
            num: int= d.popleft()
            if not d:
                break
            if num == greatest_num:
                greatest_num = max(d)

            output.append(greatest_num)

        output.append(-1)
        return output