feat(DP): new problem formated

delete-and-earn/src/ac.cpp

@@ -0,0 +1,37 @@
+#include <bits/stdc++.h>
+
+typedef long long ll;
+using namespace std;
+
+/*
+pick a number and gain n[i] points
+delete all numbers equal to n[i] - 1 and n[i] + 1
+the maximum that I can get in number n[i] is
+max (dp[i - 1], dp[i - 2] + points(i))
+*/
+
+ll deleteAndEarn(vector<int>& nums) {
+   unordered_map<int, int> freq;
+   int maxN = INT_MIN;
+   for (int i : nums) {
+      maxN = max(maxN, i);
+      freq[i]++;
+   }
+   
+   int N = maxN;
+   vector<ll> dp(N + 1, 0);
+   dp[1] = freq[1];
+   for (int i = 2; i <= N; i++) {
+      dp[i] = max(freq[i] * i + dp[i - 2], dp[i - 1]);
+   }
+
+   return dp[N];
+}
+
+int main(){
+   int n; cin >> n;
+   vector<int> nums(n);
+   for (int i = 0; i < n; i++) cin >> nums[i];
+   cout << deleteAndEarn(nums) << endl;
+   return 0;
+}