<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 {
public:

    int f(int i, vector<int> &v, vector<int> &hsh, vector<int> &dp)
    {
        int n = v.size();
        if(i == n - 1) return v[i] * hsh[v[i]];
        if(i >= n) return 0;
        if(dp[i] != -1) return dp[i];
        
        int ans = f(i + 1, v, hsh, dp);
        if(v[i + 1] == v[i] + 1)
        {
            ans = max(ans, v[i] * hsh[v[i]] + f(i + 2, v, hsh, dp));
        }
        else
        {
            ans = max(ans, v[i] * hsh[v[i]] + f(i + 1, v, hsh, dp));
        }
        return dp[i] = ans;
    }

    int deleteAndEarn(vector<int>& nums) {
        vector<int> hsh(1e4 + 5);
        int n = nums.size();
        for(int i = 0; i < n; ++i)
        {
            ++hsh[nums[i]];
        }
        vector<int> v,dp(1e4 + 5, -1);
        for(int i = 1; i < hsh.size(); ++i)
        {
            if(hsh[i] > 0) v.push_back(i);
        }
        return f(0, v, hsh, dp);
    }
};
20149