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740. Delete And Earn

Array Hash Table Dynamic Programming

Problem - Delete And Earn

Medium

You are given an integer array nums. You want to maximize the number of points you get by performing the following operation any number of times:

  • Pick any nums[i] and delete it to earn nums[i] points. Afterwards, you must delete every element equal to nums[i] - 1 and every element equal to nums[i] + 1.

Return the maximum number of points you can earn by applying the above operation some number of times.

 

Example 1:

Input: nums = [3,4,2]
Output: 6
Explanation: You can perform the following operations:
- Delete 4 to earn 4 points. Consequently, 3 is also deleted. nums = [2].
- Delete 2 to earn 2 points. nums = [].
You earn a total of 6 points.

Example 2:

Input: nums = [2,2,3,3,3,4]
Output: 9
Explanation: You can perform the following operations:
- Delete a 3 to earn 3 points. All 2's and 4's are also deleted. nums = [3,3].
- Delete a 3 again to earn 3 points. nums = [3].
- Delete a 3 once more to earn 3 points. nums = [].
You earn a total of 9 points.

 

Constraints:

  • 1 <= nums.length <= 2 * 104
  • 1 <= nums[i] <= 104

Solutions

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class Solution:
    def deleteAndEarn(self, nums: List[int]) -> int:
        max_num = 0

        for num in nums:
            max_num = max(max_num, num)

        total = [0] * (max_num + 1)
        for num in nums:
            total[num] += num

        first = total[0]
        second = max(total[0], total[1])

        for i in range(2, max_num + 1):
            current = max(first + total[i], second)
            first = second
            second = current

        return second

Submission Stats:

  • Runtime: 7 ms (79.66%)
  • Memory: 19.1 MB (93.26%)