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1770. Maximum Score from Performing Multiplication Operations

Difficulty Topics

Description

You are given two 0-indexed integer arrays nums and multipliers of size n and m respectively, where n >= m.

You begin with a score of 0. You want to perform exactly m operations. On the ith operation (0-indexed) you will:

  • Choose one integer x from either the start or the end of the array nums.
  • Add multipliers[i] * x to your score.
    • Note that multipliers[0] corresponds to the first operation, multipliers[1] to the second operation, and so on.
  • Remove x from nums.

Return the maximum score after performing m operations.

 

Example 1:

Input: nums = [1,2,3], multipliers = [3,2,1]
Output: 14
Explanation: An optimal solution is as follows:
- Choose from the end, [1,2,3], adding 3 * 3 = 9 to the score.
- Choose from the end, [1,2], adding 2 * 2 = 4 to the score.
- Choose from the end, [1], adding 1 * 1 = 1 to the score.
The total score is 9 + 4 + 1 = 14.

Example 2:

Input: nums = [-5,-3,-3,-2,7,1], multipliers = [-10,-5,3,4,6]
Output: 102
Explanation: An optimal solution is as follows:
- Choose from the start, [-5,-3,-3,-2,7,1], adding -5 * -10 = 50 to the score.
- Choose from the start, [-3,-3,-2,7,1], adding -3 * -5 = 15 to the score.
- Choose from the start, [-3,-2,7,1], adding -3 * 3 = -9 to the score.
- Choose from the end, [-2,7,1], adding 1 * 4 = 4 to the score.
- Choose from the end, [-2,7], adding 7 * 6 = 42 to the score. 
The total score is 50 + 15 - 9 + 4 + 42 = 102.

 

Constraints:

  • n == nums.length
  • m == multipliers.length
  • 1 <= m <= 300
  • m <= n <= 105
  • -1000 <= nums[i], multipliers[i] <= 1000

Solution

maximum-score-from-performing-multiplication-operations.py
class Solution:
    def maximumScore(self, nums: List[int], mul: List[int]) -> int:
        dp = [0] * (len(mul) + 1)

        for m in range(len(mul) - 1, -1, -1):
            pd = [0] * (m + 1)
            for l in range(m, -1, -1):
                pd[l] = max(dp[l + 1] + mul[m] * nums[l], 
                            dp[l] + mul[m] * nums[~(m - l)])
            dp = pd

        return dp[0]