3457. Eat Pizzas!

You are given an integer array pizzas of size n, where pizzas[i] represents the weight of the ith pizza. Every day, you eat exactly 4 pizzas. Due to your incredible metabolism, when you eat pizzas of weights W, X, Y, and Z, where W <= X <= Y <= Z, you gain the weight of only 1 pizza!

• On odd-numbered days (1-indexed), you gain a weight of Z.
• On even-numbered days, you gain a weight of Y.

Find the maximum total weight you can gain by eating all pizzas optimally.

Note: It is guaranteed that n is a multiple of 4, and each pizza can be eaten only once.

class Solution {
public:
    long long maxWeight(vector<int>& pizzas) {
        int n = pizzas.size(), day = n / 4, even = day / 2, odd = day - even;
        sort(begin(pizzas), end(pizzas));
        long long res = 0;
        for(int i = 0; i < odd; i++) res += pizzas[n-i-1];
        for(int i = odd + day * 2; i < n - odd; i += 2) res += pizzas[i];
        return res;
    }
};