HackerRank Lower Bound-STL
Although you've probably already solved this problem, I'll still post my review for completion's sake.
1. Performance
Just as Loki said, you should use std::lower_bound() and std::distance() to solve this task, because std::find() has higher complexity.
2. General tips

Do not include unused libraries (in this case, &lt;cmath&gt; and &lt;cstdio&gt;).

Only declare variables when you need them. Declaring all the variables at the beginning of the program is old C style practice, which is discouraged in C++.

Prefer prefix to postfix operator++. The postfix version creates a copy, so if you do not need that copy, you should use the prefix version.

If you have access to C++11, you should consider using auto more. It'll make your code easier to read and save you some typing.

You can safely omit return 0 from main();



[C++11: 3.6.1/5]: A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing return 0;.


Give your variables better names. Although other variable names in your code are good, a vector named v is not very descriptive.

Use const_iterators for functions that do not alter the original range.


3. Final code
#include &lt;vector&gt;
#include &lt;iostream&gt;
#include &lt;algorithm&gt;

int main() {
    int N;
    std::cin &gt;&gt; N;
    
    std::vector&lt;int&gt; numbers(N);
    //populate the vector
     for(int i = 0; i &lt; N; ++i) {
         std::cin &gt;&gt; numbers[i];
     }
    
    int queryLength;
    std::cin &gt;&gt; queryLength;    

    for(int j = 0; j &lt; queryLength; ++j) {
        int query;
        std::cin &gt;&gt; query;
        auto lowerBoundIt = std::lower_bound(numbers.cbegin(), numbers.cend(), query);
        if(*lowerBoundIt == query) {
            std::cout &lt;&lt; &quot;Yes &quot;;
        }
        else {
            std::cout &lt;&lt; &quot;No &quot;;
        }
        std::cout &lt;&lt; std::distance(numbers.cbegin(), lowerBoundIt) + 1 &lt;&lt; '\n';
    }
}