740. Delete and Earn

Delete and Earn (LeetCode 740) is a Medium Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Dynamic Programming (DP) Patterns pattern, in the 1D Array (Fibonacci Style) subpattern.

How to solve Delete and Earn

Delete and Earn is a Fibonacci Style DP problem, part of Dynamic Programming (DP) Patterns. Solve problems with Fibonacci-like recurrence: climbing stairs, house robber, decode ways.

Work towards the solution in these steps:

1. If you take a number, you might as well take them all. Keep track of what the value is of the subset of the input with maximum M when you either take or don't take M.

The reference solution runs in O(n) time and O(1) space.

The Delete and Earn solution and editorial walks through the full approach with reference code.

Problem statement

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

Topics and companies

Topics: Array, Hash Table, Dynamic Programming.

Reported in interviews at Goldman Sachs.

How to practise Delete and Earn on Thita.ai

Starter code is provided in C, C#, C++, Go, Java, JavaScript and Python. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(n) time and O(1) space.

Open Delete and Earn in the code editor, or read the Delete and Earn editorial for a worked solution with its approach and complexity analysis.

Where Delete and Earn sits in the DSA pattern sheet

• Dynamic Programming (DP) Patterns pattern guide
• 1D Array (Fibonacci Style) subpattern
• The full DSA patterns sheet

Problems related to Delete and Earn

Other problems that use the same 1D Array (Fibonacci Style) and Dynamic Programming (DP) Patterns techniques:

• Climbing Stairs — Easy, same subpattern
• Decode Ways — Medium, same subpattern
• Fibonacci Number — Easy, same subpattern
• House Robber — Medium, same subpattern
• House Robber II — Medium, same subpattern
• Integer Break — Medium, same subpattern

Delete and Earn FAQ