void Solver::pointing_pair(const sud_list<sud_node> * occurrences,
const niner & n, iter_over what, outcome& pp_outcome) {
for (u i = 0; i < 9; ++i) {
u candidate = i + 1;
if (occurrences[i].size() == 2) {
const u& row_1 = occurrences[i][0].rw;
const u& row_2 = occurrences[i][1].rw;
const u& col_1 = occurrences[i][0].cm;
const u& col_2 = occurrences[i][1].cm;
const bool same_row = row_1 == row_2;
const bool same_col = col_1 == col_2;
// if (row_1 == 6 && row_2 == 6 && col_1 == 3 && col_2 == 5) {
// grid.print_possible_values();
// cout << "stop here";
// }
if (what != SQUARES) {
if (zero(row_1) == zero(row_2) && zero(col_1) == zero(col_2)) {
niner sqr_n = grid.get_niner(SQUARES, square_index(row_1, col_1));
for (u index = 0; index < 9; ++index) {
Cell& cell = *(sqr_n[index]);
const sud_node& node = cell.node();
if ((node.rw == row_1 && node.cm == col_1) ||
(node.rw == row_2 && node.cm == col_2)) {
continue;
}
rm_pointing_pair(cell, candidate, pp_outcome);
if (pp_outcome == NEW_VALUE) return;
}
}
} else if (what == SQUARES) {
u zero_col = zero(col_1);
u zero_row = zero(row_1);
for (u index = 0; index < 9; ++index) {
if (same_row || same_col) {
// skip the three cells on the same row or column
if ((same_row && zero(index) == zero_col) ||
(same_col && zero(index) == zero_row)) {
continue;
}
Cell & cell = same_row ? grid.cell(row_1, index) :
grid.cell(index, col_1);
rm_pointing_pair(cell, candidate, pp_outcome);
if (pp_outcome == NEW_VALUE) return;
}
}
}
}
}
}
inline bool check_position(unsigned int a,unsigned int b,unsigned int value)
{
if(row[a][value]||column[b][value]||square[square_index(a,b)][value]) return false;
return true;
}
inline void flag_position(unsigned int a,unsigned int b)
{
row[a][map[a][b]]=!row[a][map[a][b]];
column[b][map[a][b]]=!column[b][map[a][b]];
square[square_index(a,b)][map[a][b]]=!square[square_index(a,b)][map[a][b]];
}