3993. Maximum Value of an Alternating Sequence

You are given three integers n, s, and m.

A sequence seq of integers of length n is considered valid if:

• seq[0] = s.
• The sequence is alternating, meaning that either:
  • seq[0] > seq[1] < seq[2] > ..., or
  • seq[0] < seq[1] > seq[2] < ....
• For every adjacent pair, |seq[i] - seq[i - 1]| <= m.

A sequence of length 1 is considered alternating.

Return the maximum possible element that can appear in any valid sequence.

class Solution {
public:
    long long maximumValue(int n, int s, int m) {  
        return n == 1 ? s : s + ((n / 2 - 1) * 1ll * (m - 1)) + (n / 2 ? m : 0);
    }
};