Binary Search Framework

Use Binary Search to find the first/last element with a property in a sorted array.

l: first position in your consideration
h: last position in your consideration, even can larger than the last index of the array

while (l < h) {
    // first element
    m_l = l + (h - l) / 2
    if (!Satisfy(m_l)) {
        l = m + 1
    } else {
        h = m
    }
    /*
    // last element
    m_h = l + (h - l) / 2 + 1
    if (!Satisfy(m_h)) {
        h = m - 1
    } else {
        l = m
    }
    */
}

The idea is that if the mid point satisfies a property, then keep the opposite bound of round at mid, otherwise move the corresponding bound toward mid exceed 1.
Finally its true that l == h