396. Rotate Function

You are given an integer array nums of length n.

Assume arrk to be an array obtained by rotating nums by k positions clock-wise. We define the rotation function F on nums as follow:

• F(k) = 0 arrk[0] + 1 arrk[1] + … + (n - 1) * arrk[n - 1].

Return the maximum value of F(0), F(1), …, F(n-1).

c++

class Solution {
public:
    int maxRotateFunction(vector<int>& nums) {
        long acc = 0, res = 0, tot = 0, sz = nums.size();
        for(int i = 0; i < sz; i++) {
            acc += nums[i];
            tot += i * nums[i];
        }
        res = tot;
        for(int i = 0; i < sz; i++) {
            tot = tot + acc - sz * nums[sz - 1 - i];
            res = max(tot, res);
        }

        return res;
    }
};