2460-apply-operations-to-an-array.py

from typing import List
import unittest

# https://leetcode.com/problems/apply-operations-to-an-array/

# python3 -m unittest twopointers/2460-apply-operations-to-an-array.py


class Solution(unittest.TestCase):
    # Approach: Brute-Force
    # Time: O(n)
    # Space: O(1)
    def applyOperations(self, nums: List[int]) -> List[int]:
        n, left = len(nums), 0
        for idx in range(n):
            if nums[idx] == 0:
                continue
            if idx < n - 1 and nums[idx] == nums[idx + 1]:
                nums[left] = nums[idx] * 2
                nums[idx + 1] = 0
            else:
                nums[left] = nums[idx]
            left += 1
        while left < n:
            nums[left] = 0
            left += 1
        return nums

    def test(self):
        for nums, expected in [
            ([1, 2, 2, 1, 1, 0], [1, 4, 2, 0, 0, 0]),
            ([0, 1], [1, 0]),
            ([1, 4, 0, 2, 0, 0], [1, 4, 2, 0, 0, 0]),
            (
                [847, 847, 0, 0, 0, 399, 416, 416, 879, 879, 206, 206, 206, 272],
                [1694, 399, 832, 1758, 412, 206, 272, 0, 0, 0, 0, 0, 0, 0],
            ),
        ]:
            output = self.applyOperations(nums)
            self.assertEqual(expected, output, f"expected: {expected}, output: {output}")