Alice’s christmas tree

• Time : $O(nlogn + nk)$
• Space : $O(k)$

#include <bits/stdc++.h>
using namespace std;
int largest_visible_area(int k, std::vector<std::pair<int, int>> cylinders) {
    vector<int> dp(k, INT_MIN); dp[0] = 0;
    sort(rbegin(cylinders), rend(cylinders));
    for(int i = 0; i < cylinders.size(); i ++) {
        auto [r,m] = cylinders[i];
        if(i and cylinders[i-1].first == r) continue;
        for(int j = k-1; j >= 1; j--) dp[j] = max(dp[j], dp[j-1] + m);
        dp[0] = max(dp[0], r * r + m);
    }
    return dp[k-1];
};