human
I found an interesting problem on https://leetcode.com/problems/delete-and-earn/:
Given an array nums of integers, you can perform operations on the array.

In each operation, you pick any nums[i] and delete it to earn nums[i] points.  After, you must delete every element equal to nums[i] - 1 or nums[i] + 1.

You start with 0 points.  Return the maximum number of points you can earn by applying such operations.

Example 1:

Input: nums = [3, 4, 2]
Output: 6
Explanation: 
Delete 4 to earn 4 points, consequently 3 is also deleted.
Then, delete 2 to earn 2 points. 6 total points are earned.


Example 2:

Input: nums = [2, 2, 3, 3, 3, 4]
Output: 9
Explanation: 
Delete 3 to earn 3 points, deleting both 2's and the 4.
Then, delete 3 again to earn 3 points, and 3 again to earn 3 points.
9 total points are earned.


Note:
The length of nums is at most 20000.
Each element nums[i] is an integer in the range [1, 10000].

I tried it in Python, but could not do it. Can you solve it?
assistant
#Here is the Python program you requested.

class Solution:
     def deleteAndEarn(self, nums):
         """
         :type nums: List[int]
         :rtype: int
         """
         nums.sort()
         nums.append(-1) #end symbol
         prev_max, cur_max = 0, 0
         prev = -1
         j, i = 0, 0
         while i < len(nums):
             if nums[i] == nums[j]:
                 i += 1
                 continue
             dif = i - j
             temp = dif*nums[j]
             if nums[j] == prev + 1:
                 prev_max, cur_max = cur_max, max(temp + prev_max, cur_max)
             else:
                 prev_max, cur_max = cur_max, temp + cur_max
             prev = nums[j]
             j = i
             i += 1
         return cur_max