Profit Maximization:
int ans = 0;
    int buy = v[0];
    for (int i = 1; i < n; i++)
    {
        ans = max(ans, v[i] - buy);
        buy = min(buy, v[i]);
    }

    return and;

Profit Maximization - Extended
 int ans = 0;
    int buy = v[0];
    for (int i = 1; i < n; i++)
    {
        if(v[i] > v[i-1])ans += v[i]-v[i-1];
    }

return and;


Profit Model for John:
string ans;

    for (int test = 0; test < d; test++){
        int target = profit[test];

        int f = 1;
        string res;
        int id1 = 0, id2 = 100000000;
        for (int i = 0; i < n; i++)
        {
            for (int j = i+1; j < n ; j++){

                if(price[j] - price[i] == target){
                    if(id2 - id1 > j - i){
                    res = to_string(i + 1) + ' ' + to_string(j + 1);
                    f = 0;
                    id1 = i;
                    id2 = j;
                    }
                }
            }
        }

        if(f)
            res = to_string(-1);
        if(ans.size())
            ans += ',' + res;
        else
            ans = res;
    }

    return ans;