How to eliminate array item in array 3 dimension java

Question

I had a problem to eliminate candidates in a cell sudoku, I have tried to search for candidates to fill the empty cells like below

for (int y = 0; y < 9; y++) {
        for (int x = 0; x < 9; x++)
            if(game.getNumber(x, y) == 0){
                for(int z = 1; z <=9; z++){
                    if (CekRow(game, y, z) && CekColumn(game, x, z) && CekRegion(game, x, y, z)){
                        list[y][x][z-1] = z;
                    }
                }
            }
    }

then after find empty cell and fill with the candidate, i want to eliminate possible item array like method this enter image description here. i have someone can provide the solution to eliminate array list[y][x][z].

Answer 1

Here's another possible data structure for a Sudoku board using the Java BitSet class. Each cell on the board has its possibilities tracked by a BitSet variable called possibilities.

Also shown is an example eliminateInRow method which eliminates numbers as possibilities from a row. The method includes a list of columns to skip in the row, to exempt the cells that originally caused us to do the elimination (for example the cells 7 and 9 mentioned by the OP in comments on the original question). There's also another case where if you find 3 cells all containing the possibilities (3,5,9) (for example), then you can eliminate 3,5,9 as possibilities from all other cells in the row (exempting the original 3 cells). This method will deal with both the 2-case and the 3-case, as it uses a List of integers denoting columns to skip.

import java.util.BitSet;
import java.util.List;

class SudokuCell {
    BitSet possibilities;
    CellValue value;

    SudokuCell() {

        // Initially the value of this cell is undefined
        value = CellValue.Undefined;

        possibilities = new BitSet(9);
        // Initially every value is possible
        possibilities.set(0, 9);
    }

    // clears the possibility of 'number' from this cell
    void clear(int number) {
        possibilities.clear(number - 1);
        // If there is only one possibility left
        if (possibilities.cardinality() == 1) {

            // Set value of the cell to that possibility
            int intValue = possibilities.nextSetBit(0);
            value = CellValue.fromInteger(intValue);
        }
    }

    // returns the value of this square if it is defined
    int getValue() throws Exception {
        if (value == CellValue.Undefined) {
            throw new Exception("Undefined cell value");
        }
        return CellValue.toInteger(value);
    }

    // returns whether 'num' is still possible in this cell
    boolean isPossible(int num) {
        return possibilities.get(num-1);
    }
}

public class SudokuBoard {
    SudokuCell[][] sudokuBoard;

    // constructor
    SudokuBoard() {
        sudokuBoard = new SudokuCell[9][9];
        for (int row = 0; row < 9; row++) {
            for (int col = 0; col < 9; col++) {
                sudokuBoard[row][col] = new SudokuCell();
            }
        }

    }

    // eliminate the possibility of 'num' from row 'row'
    // skipping columns in List skipCols
    void eliminateInRow(int row, int num, List<Integer> skipCols) {
        for (int col = 0; col < 9; col++) {
            if (!skipCols.contains(col)) {
                sudokuBoard[row][col].clear(num);
            }
        }

    }

}

Below is the code for the enum CellValue, which is optional:

enum CellValue {
    Undefined, One, Two, Three, Four, Five, Six, Seven, Eight, Nine;
    public static CellValue fromInteger(int x) {
        switch (x) {
        case 0:
            return Undefined;
        case 1:
            return One;
        case 2:
            return Two;
        case 3:
            return Three;
        case 4:
            return Four;
        case 5:
            return Five;
        case 6:
            return Six;
        case 7:
            return Seven;
        case 8:
            return Eight;
        case 9:
            return Nine;
        }
        return null;
    }

    public static int toInteger(CellValue value) throws Exception {
        switch (value) {
        case Undefined:
            throw new Exception("Undefined cell value");
        case One:
            return 1;
        case Two:
            return 2;
        case Three:
            return 3;
        case Four:
            return 4;
        case Five:
            return 5;
        case Six:
            return 6;
        case Seven:
            return 7;
        case Eight:
            return 8;
        case Nine:
            return 9;
        }
        throw new Exception("Undefined Cell Value");
    }
}