bool BoardGenerator::handleNakedPairs(int round){
for (int position=0; position<BOARD_SIZE; position++){
int possibilities = countPossibilities(position);
if (possibilities == 2){
int row = cellToRow(position);
int column = cellToColumn(position);
int section = cellToSectionStartCell(position);
for (int position2=position; position2<BOARD_SIZE; position2++){
if (position != position2){
int possibilities2 = countPossibilities(position2);
if (possibilities2 == 2 && arePossibilitiesSame(position, position2)){
if (row == cellToRow(position2)){
bool doneSomething = false;
for (int column2=0; column2<9; column2++){
int position3 = rowColumnToCell(row,column2);
if (position3 != position && position3 != position2 && removePossibilitiesInOneFromTwo(position, position3, round)){
doneSomething = true;
}
}
if (doneSomething){
if (recordHistory) addHistoryItem(new LogItem(round, LogItem::NAKED_PAIR_ROW, 0, position));
return true;
}
}
if (column == cellToColumn(position2)){
bool doneSomething = false;
for (int row2=0; row2<9; row2++){
int position3 = rowColumnToCell(row2,column);
if (position3 != position && position3 != position2 && removePossibilitiesInOneFromTwo(position, position3, round)){
doneSomething = true;
}
}
if (doneSomething){
if (recordHistory) addHistoryItem(new LogItem(round, LogItem::NAKED_PAIR_COLUMN, 0, position));
return true;
}
}
if (section == cellToSectionStartCell(position2)){
bool doneSomething = false;
int secStart = cellToSectionStartCell(position);
{for (int i=0; i<3; i++){
for (int j=0; j<3; j++){
int position3=secStart+i+(9*j);
if (position3 != position && position3 != position2 && removePossibilitiesInOneFromTwo(position, position3, round)){
doneSomething = true;
}
}
}}
if (doneSomething){
if (recordHistory) addHistoryItem(new LogItem(round, LogItem::NAKED_PAIR_SECTION, 0, position));
return true;
}
}
}
}
}
}
}
return false;
}
boolean guess(unsigned short* sudoku, int recursionLevel)
{
if(recursionLevel >= MAX_DEPTH) // max
return false;
unsigned int cell, numPossibilities;
for(cell = 0; cell < 256; cell++)
for(numPossibilities = 2; numPossibilities < 16; numPossibilities++)
{
if(countPossibilities(sudoku[cell]) != numPossibilities)
continue;
unsigned int bit;
for(bit = 0; bit < 16; bit++)
{
if(!(sudoku[cell] & (1 << bit)))
continue;
copySudoku(sudoku, sudokuGuess[recursionLevel]);
// make a guess
sudokuGuess[recursionLevel][cell] &= (1 << bit);
guessConflict[recursionLevel] = false;
solve(sudokuGuess[recursionLevel], recursionLevel);
if(!guessConflict[recursionLevel])
continue;
// remove impossible guess from source sudoku
sudoku[cell] &= ~(1 << bit);
if(recursionLevel <= 0)
{
printf("Conflict at cell %d for value %c\n", cell, 'A' + bit);
}
return true;
}
}
return false;
}
boolean isFixed(unsigned short value)
{
return countPossibilities(value) == 1;
}