问题在于，在大多数情况下无法使用随机数生成完整的电路板，如果无法找到下一个单元，则必须使用回溯。我曾经写过一个数独游戏，所以这是生成填充板的代码。
这是Cell类。
public class SudokuCell implements Serializable {
private int value;
private boolean filled;
private HashSet<Integer> tried;
public SudokuCell() {
filled = false;
tried = new HashSet();
}
public boolean isFilled() {
return filled;
}
public int get() {
return value;
}
public void set(final int number) {
filled = true;
value = number;
tried.add(number);
}
public void clear() {
value = 0;
filled = false;
}
public void reset() {
clear();
tried.clear();
}
public void show() {
filled = true;
}
public void hide() {
filled = false;
}
public boolean isTried(final int number) {
return tried.contains(number);
}
public void tryNumber(final int number) {
tried.add(number);
}
public int numberOfTried() {
return tried.size();
}
}
这是Field类（将所有数据保留在一个对象中非常方便）。
public class SudokuField implements Serializable {
private final int blockSize;
private final int fieldSize;
private SudokuCell[][] field;
public SudokuField(final int blocks) {
blockSize = blocks;
fieldSize = blockSize * blockSize;
field = new SudokuCell[fieldSize][fieldSize];
for (int i = 0; i < fieldSize; ++i) {
for (int j = 0; j < fieldSize; ++j) {
field[i][j] = new SudokuCell();
}
}
}
public int blockSize() {
return blockSize;
}
public int fieldSize() {
return fieldSize;
}
public int variantsPerCell() {
return fieldSize;
}
public int numberOfCells() {
return fieldSize * fieldSize;
}
public void clear(final int row, final int column) {
field[row - 1][column - 1].clear();
}
public void clearAllCells() {
for (int i = 0; i < fieldSize; ++i) {
for (int j = 0; j < fieldSize; ++j) {
field[i][j].clear();
}
}
}
public void reset(final int row, final int column) {
field[row - 1][column - 1].reset();
}
public void resetAllCells() {
for (int i = 0; i < fieldSize; ++i) {
for (int j = 0; j < fieldSize; ++j) {
field[i][j].reset();
}
}
}
public boolean isFilled(final int row, final int column) {
return field[row - 1][column - 1].isFilled();
}
public boolean allCellsFilled() {
for (int i = 0; i < fieldSize; ++i) {
for (int j = 0; j < fieldSize; ++j) {
if (!field[i][j].isFilled()) {
return false;
}
}
}
return true;
}
public int numberOfFilledCells() {
int filled = 0;
for (int i = 1; i <= fieldSize; ++i) {
for (int j = 1; j <= fieldSize; ++j) {
if (isFilled(i, j)) {
++filled;
}
}
}
return filled;
}
public int numberOfHiddenCells() {
return numberOfCells() - numberOfFilledCells();
}
public int get(final int row, final int column) {
return field[row - 1][column - 1].get();
}
public void set(final int number, final int row, final int column) {
field[row - 1][column - 1].set(number);
}
public void hide(final int row, final int column) {
field[row - 1][column - 1].hide();
}
public void show(final int row, final int column) {
field[row - 1][column - 1].show();
}
public void tryNumber(final int number, final int row, final int column) {
field[row - 1][column - 1].tryNumber(number);
}
public boolean numberHasBeenTried(final int number, final int row, final int column) {
return field[row - 1][column - 1].isTried(number);
}
public int numberOfTriedNumbers(final int row, final int column) {
return field[row - 1][column - 1].numberOfTried();
}
public boolean checkNumber@R_281_2419@(final int number, final int row, final int column) {
int r = row, c = column;
if (r % blockSize == 0) {
r -= blockSize - 1;
} else {
r = (r / blockSize) * blockSize + 1;
}
if (c % blockSize == 0) {
c -= blockSize - 1;
} else {
c = (c / blockSize) * blockSize + 1;
}
for (int i = r; i < r + blockSize; ++i) {
for (int j = c; j < c + blockSize; ++j) {
if (field[i - 1][j - 1].isFilled() && (field[i - 1][j - 1].get() == number)) {
return false;
}
}
}
return true;
}
public boolean checkNumberRow(final int number, final int row) {
for (int i = 0; i < fieldSize; ++i) {
if (field[row - 1][i].isFilled() && field[row - 1][i].get() == number) {
return false;
}
}
return true;
}
public boolean checkNumberColumn(final int number, final int column) {
for (int i = 0; i < fieldSize; ++i) {
if (field[i][column - 1].isFilled() && field[i][column - 1].get() == number) {
return false;
}
}
return true;
}
public boolean checkNumberField(final int number, final int row, final int column) {
return (checkNumber@R_281_2419@(number, row, column)
&& checkNumberRow(number, row)
&& checkNumberColumn(number, column));
}
public int numberOfPossibleVariants(final int row, final int column) {
int result = 0;
for (int i = 1; i <= fieldSize; ++i) {
if (checkNumberField(i, row, column)) {
++result;
}
}
return result;
}
public boolean isCorrect() {
for (int i = 0; i < fieldSize; ++i) {
for (int j = 0; j < fieldSize; ++j) {
if (field[i][j].isFilled()) {
int value = field[i][j].get();
field[i][j].hide();
boolean correct = checkNumberField(value, i + 1, j + 1);
field[i][j].show();
if (!correct) {
return false;
}
}
}
}
return true;
}
public Index nextCell(final int row, final int column) {
int r = row, c = column;
if (c < fieldSize) {
++c;
} else {
c = 1;
++r;
}
return new Index(r, c);
}
public Index cellWithMinVariants() {
int r = 1, c = 1, min = 9;
for (int i = 1; i <= fieldSize; ++i) {
for (int j = 1; j <= fieldSize; ++j) {
if (!field[i - 1][j - 1].isFilled()) {
if (numberOfPossibleVariants(i, j) < min) {
min = numberOfPossibleVariants(i, j);
r = i;
c = j;
}
}
}
}
return new Index(r, c);
}
public int getRandomIndex() {
return (int) (Math.random() * 10) % fieldSize + 1;
}
}
最后是充满游戏板的功能
private void generateFullField(final int row, final int column) {
if (!field.isFilled(field.fieldSize(), field.fieldSize())) {
while (field.numberOfTriedNumbers(row, column) < field.variantsPerCell()) {
int candidate = 0;
do {
candidate = field.getRandomIndex();
} while (field.numberHasBeenTried(candidate, row, column));
if (field.checkNumberField(candidate, row, column)) {
field.set(candidate, row, column);
Index nextCell = field.nextCell(row, column);
if (nextCell.i <= field.fieldSize()
&& nextCell.j <= field.fieldSize()) {
generateFullField(nextCell.i, nextCell.j);
}
} else {
field.tryNumber(candidate, row, column);
}
}
if (!field.isFilled(field.fieldSize(), field.fieldSize())) {
field.reset(row, column);
}
}
}
关键是在继续操作之前，您要保存已经为每个单元格尝试过的数字。如果要走到尽头，您只需要为上一个单元格尝试另一个数字即可。如果不可能，请擦除该单元格并向后退一个单元格。迟早您会完成它。（精算只需要很少的时间）。
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