<p>You are given an integer array <code>nums</code>. You want to maximize the number of points you get by performing the following operation any number of times:</p>

<ul>
	<li>Pick any <code>nums[i]</code> and delete it to earn <code>nums[i]</code> points. Afterwards, you must delete <b>every</b> element equal to <code>nums[i] - 1</code> and <strong>every</strong> element equal to <code>nums[i] + 1</code>.</li>
</ul>

<p>Return <em>the <strong>maximum number of points</strong> you can earn by applying the above operation some number of times</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [3,4,2]
<strong>Output:</strong> 6
<strong>Explanation:</strong> 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.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,2,3,3,3,4]
<strong>Output:</strong> 9
<strong>Explanation:</strong> You can perform the following operations:
- Delete a 3 to earn 3 points. All 2&#39;s and 4&#39;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.</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 2 * 10<sup>4</sup></code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
</ul>

class Solution {
    int recurseScore(unordered_map<int, int>& dp, unordered_map<int, int>& occurrences, int l, int r) {
        if (r < l) {
            return 0;
        }

        if (dp.find(r) == dp.end()) {
            return dp[r] = max(occurrences[r] * r + recurseScore(dp, occurrences, l, r - 2), occurrences[r - 1] * (r - 1) + recurseScore(dp, occurrences, l, r - 3));
        }

        return dp[r];
    }

public:
    int deleteAndEarn(vector<int>& nums) {
        sort(nums.begin(), nums.end());

        unordered_map<int, int> occurrences;
        for (int num : nums) {
            ++occurrences[num];
        }

        int totalScore = 0;
        unordered_set<int> processed;
        for (int i = nums.size() - 1; i >= 0; --i) {
            int r = nums[i];
            if (processed.find(nums[i]) != processed.end()) {
                continue;
            }
            processed.insert(r);

            int l = r;
            while (occurrences[l - 1] != 0) {
                --l;
                processed.insert(l);
            }

            unordered_map<int, int> dp;
            totalScore += recurseScore(dp, occurrences, l, r);
        }

        return totalScore;
    }
};
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