LeetCode [740] Delete and Earn

 740. Delete and Earn

Medium

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].

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class Solution { /* p2 p1 p0 p2 p1 */ public int deleteAndEarn(int[] nums) { int n = 10001; int[] sum = new int[n]; int max = 0; for(int i : nums) sum[i] += i; int p1 = 0, p2 = 0; for(int i=0; i<n; ++i){ //max earned point until current position int p0 = Math.max(sum[i]+p2, p1); p2 = Math.max(p1, p2); p1 = p0; max = Math.max(max, p0); } return max; } }