740. 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.

 

Constraints:

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

Rust Solution

struct Solution;

impl Solution {
    fn delete_and_earn(nums: Vec<i32>) -> i32 {
        let n = 10001;
        let mut sum: Vec<i32> = vec![0; n];
        let mut dp: Vec<i32> = vec![0; n];
        for x in nums {
            sum[x as usize] += x;
        }
        dp[1] = sum[1];
        for i in 2..n {
            dp[i] = i32::max(sum[i] + dp[i - 2], dp[i - 1]);
        }
        dp[n - 1]
    }
}

#[test]
fn test() {
    let nums = vec![3, 4, 2];
    let res = 6;
    assert_eq!(Solution::delete_and_earn(nums), res);
    let nums = vec![2, 2, 3, 3, 3, 4];
    let res = 9;
    assert_eq!(Solution::delete_and_earn(nums), res);
}

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