<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 curr , vector<pair<int,int>>& arr,vector<int>& dp){
        int n=arr.size();
        if(curr>=n)return 0;
        if(dp[curr]!=0)return dp[curr];
        int take=0,notTake=0;
        notTake=f(curr+1,arr,dp);
        if(curr==n-1){
            take=arr[curr].first*arr[curr].second;
        }else{
            if(arr[curr+1].first-1==arr[curr].first)take=arr[curr].first*arr[curr].second+f(curr+2,arr,dp);
            else take=arr[curr].first*arr[curr].second+f(curr+1,arr,dp);
        }
       return dp[curr]=max(take,notTake);
    }
    int deleteAndEarn(vector<int>& nums) {
        int n= nums.size();
        sort(nums.begin(),nums.end());
        vector<pair<int,int>> arr;
        int i=0;
        while(i<n){
            int count=0;
            int start=i;
            while(i<n && nums[i]==nums[start]){
                i++;
                count++;
            }
            arr.push_back({nums[start],count});
        }
        int l = arr.size();
        vector<int> dp(l,0);
        return f(0,arr,dp);
    }
};
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