How to use upper_bound on array of pair<int,int> in C++?

Question

I want to use upper_bound on array of pair and that too using a comparator function that compares the second parameter of pair. Please help.

Code:

bool cmp(const pair<int,int> &p1, const pair<int,int> &p2)
{
    return p1.second<p2.second;
}

int subsets(pair<int,int> time[], int p)
{
    if(p == 0)  return 1;
    int j = upper_bound(time, time+p, time[p], cmp) - time;
}

EDIT: I have corrected the return type but I don't seem to get what I wanted as an output.
I have an array of pair<int,int> named time which contains the start and end time as the first and second parameter respectively and sorted according to end time in increasing fashion.

Presently I am at index p. I want to find the maximum index of the array( = j), such that time[j].second <= time[p].first.
Eg.
time = { (1,5), (4,7) , (6, 12) } and if p = 2(0 based indexing) then j should be = 0 (as 5 <= 6 but 7 > 6) but upper_bound gives me j = 2.

How can I achieve this?

Answer 1

The following code does the job :)

bool compareit(int n, pair<int,int> &p)
{
    return p.second > n;
}

int subsets(pair<int,int> time[], int p)
{
    if(p == 0)  return 1;
    int j = upper_bound(time, time+p, time[p].first, compareit) - time;
}