740. Delete and Earn

Medium (Trung bình) C++ 🔗 Xem trên LeetCode

📋 Đề Bài

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

🧠 Thuật Toán & Kỹ Thuật

Dynamic Programming (Quy hoạch động)
⏱️ Thời gian O(n²)
💾 Không gian O(n)

💻 Lời Giải

C++ 0740-delete-and-earn.cpp 
class Solution {
public:
    int deleteAndEarn(vector<int>& nums) {
        const int n = 1e4;
        int dp[n + 1] = {};
        for (int num : nums) {
            dp[num] += num;
        }
        for (int i = 2; i <= n; ++i) {
            dp[i] = max(dp[i - 1], dp[i - 2] + dp[i]);
        }
        return dp[n];
    }
};