bool hiddenSingles(Puzzle &puzzle)
{
for (int i = 0; i < 9; ++i)
for (int j = 0; j < 9; ++j)
if (puzzle.getCellNumber(i, j) == 0)
{
for (int k = 0; k < puzzle.getPossibleValues(i, j).size(); ++k)
{
if (!puzzle.posInRegion(i, j, puzzle.getPossibleValues(i, j)[k]) || !puzzle.posInColumn(i, j, puzzle.getPossibleValues(i, j)[k]) || !puzzle.posInRow(i, j, puzzle.getPossibleValues(i, j)[k]))
{
puzzle.setCellNumber(i, j, puzzle.getPossibleValues(i, j)[k]);
puzzle.getPossibleValues(i, j).clear();
puzzle.updateRowColumnRegion(i, j);
return true;
}
}
}
return false;
}
//return true if guess was correct
bool guess(Puzzle &puzzle, Puzzle &alternative)
{
for (int i = 0; i < 9; ++i)
{
for (int j = 0; j < 9; ++j)
{
if ((puzzle.getCellNumber(i, j) == 0) && !(puzzle.getPossibleValues(i, j).empty()))
{
for (int k = 0; k < puzzle.getPossibleValues(i, j).size(); ++k)
{
//make an alternative puzzle that assumes the puzzle is false
//MUST MAKE A DEEP COPY
alternative.erasePossibleValue(i, j, puzzle.getPossibleValues(i, j)[k]);
//set number as guess
puzzle.setCellNumber(i, j, puzzle.getPossibleValues(i, j)[k]);
puzzle.getPossibleValues(i, j).clear(); //clear possible values after setting cell number
puzzle.updateRowColumnRegion(i, j);
return true;
}
}
else if (puzzle.getCellNumber(i, j) == 0 && puzzle.getPossibleValues(i, j).empty())
return false;
//contradiction occured...
}
}
return 0;
} //must return false for contradictions