Optimize recurrent function in MM L1 Simulation

In the modified function the same for loop was called twice, pointing to the same element in both iterations. Instead of the old-style for -> if -> break combination, the check is now done only once, being replaced with a much more concise function from std library.

Since an iterator to the first element matching the condition is returned, the behavior is exactly the same as the removed snippets

./cc @vadamico