Hello everyone! I am new to competitive coding and asking a rookie query in a blog for the first time so apologies in advance if anything is not according to norms.

I was solving this problem today 1284B - New Year and Ascent Sequence . Here is the editorial. Idea behind my solution is almost as in editorial. The issue is that my submission with custom function for upper_bound got tle verdict but when I used built in function for the same it got accepted.

I used the concept of binary search in my function so the overall complexity is still O(nlogn) which should get accepted(according to me).

ll bs(vector<ll> maxv,ll x)
{
    ll l = 0;
    ll r = maxv.size() - 1;

    ll mid;
   
    while (l <= r)
    {
        mid = (l+r)/2;
        if(maxv[mid] <= x)
        {
            l = mid + 1;
         
        }
        else
        {
            r = mid-1;
        }
        
    }
    return l;
    
}

86441251 is the submission which got tle. 86412015 is the submission which got accepted.

Thanks in advance!