Max Sum Without Adjacent Elements

• Time : $O(n)$
• Space : $O(1)$

#include <bits/stdc++.h>

int Solution::adjacent(vector<vector<int>> &A) {
    int dp = 0, dpp = 0;
    for(int i = 0; i < A[0].size(); i++) {
        int now = max(A[0][i], A[1][i]);
        int dppp = max(dp, dpp + now);
        dpp = dp;
        dp = dppp;
    }
    return max(dp,dpp);
}