/*!
* \param i The index of the symbol.
* \param c Reference that will contain the symbol at position i after the execution of the method.
* \return The number of occurrences of symbol wt[i] in the prefix [0..i-1]
* \par Time complexity
* \f$ \Order{H_0} \f$
*/
size_type inverse_select(size_type i, value_type& c)const {
assert(i < size());
if (i == 0) {
c = m_wt[0];
return 0;
}
size_type wt_ex_pos = m_bl_rank(i+1);
size_type c_runs = m_wt.inverse_select(wt_ex_pos-1, c)+1;
if (c_runs == 0)
return 0;
if (m_wt[wt_ex_pos-1] == c) {
size_type c_run_begin = m_bl_select(wt_ex_pos);
return m_bf_select(m_C_bf_rank[c] + c_runs) - m_C[c] + i - c_run_begin;
} else {
return m_bf_select(m_C_bf_rank[c] + c_runs + 1) - m_C[c];
}
}
