/*! \param i Index of the value. \f$ i \in [0..size()-1]\f$.
* Time complexity: O(log n/k)
*/
inline value_type operator[](size_type i)const {
uint8_t level = 1;
uint8_t offset = t_b;
size_type result = m_data[i];
const uint64_t* p = m_level_pointer_and_rank.data();
uint64_t ppi = (*p)+i;
while (level < m_max_level and m_overflow[ppi]) {
p += 2;
ppi = *p + (m_overflow_rank(ppi) - *(p-1));
result |= (m_data[ppi] << (offset));
++level;
offset += t_b;
}
return result;
}
