public class SudokuSolver {
public static void initializeGrid(int[][] grid, int[][] puzzle) {
for (int r = 0; r < puzzle.length; r++) {
for (int c = 0; c < puzzle[0].length; c++) {
grid [r][c] = puzzle [r][c];
}
}
}
public static void displayGrid(int[][] grid) {
for (int r = 0; r < grid.length; r++) {
if (r % 3 == 0) {
System.out.println("+---+---+---+");
}
for (int c = 0; c < grid[r].length; c++) {
if (c % 3 == 0) {
System.out.print("|");
}
displayDigits(r, c, grid);
}
System.out.print("|");
System.out.println();
}
System.out.println("+---+---+---+");
}
if (grid[r][c] == 0) {
System.out.print(' ');
}
else {
System.out.print(grid[r][c]);
}
}
public static int getEmptyCells(int[][] grid, int[][] emptyCells) {
int i = 0;
int numEmptyCells = 0;
for (int r = 0; r < grid.length; r++) {
for (int c = 0; c < grid[r].length; c++) {
if (grid[r][c] == 0) {
emptyCells[i][0] = r;
emptyCells[i][1] = c;
numEmptyCells++;
i++;
}
}
}
return numEmptyCells;
}
private static boolean hasNoDuplicates(int[] digitsList) {
for (int j = 0; j < digitsList.length; j++) {
for (int k = j + 1; k < digitsList.length; k++) {
if (digitsList[j] == digitsList[k] && digitsList[j] != 0)
return false;
}
}
return true;
}
private static boolean checkCurrentRow(int[][] grid, int currentRow) {
int[] digitsList = new int[grid.length];
for (int c = 0; c < digitsList.length; c++) {
digitsList[c] = grid[currentRow][c];
}
if (hasNoDuplicates(digitsList)) {
return true;
}
return false;
}
private static boolean checkCurrentCol(int[][] grid, int currentCol) {
int[] digitsList = new int[grid.length];
for (int i = 0; i < digitsList.length; i++) {
digitsList[i] = grid[i][currentCol];
}
if (hasNoDuplicates(digitsList)) {
return true;
}
return false;
}
private static boolean checkCurrentRegion(int[][] grid, int currentRow, int currentCol) {
int[] digitsList = new int[grid.length];
currentRow = (currentRow / 3) * 3;
currentCol = (currentCol / 3) * 3;
int i = 0;
for (int r = 0; r < 3; r++) {
for (int c = 0; c < 3; c++) {
digitsList[i] = grid[currentRow + r][currentCol + c];
i++;
}
}
if (hasNoDuplicates(digitsList)) {
return true;
}
return false;
}
public static boolean isConsistent(int[][] grid, int currentRow, int currentCol) {
if (checkCurrentRow(grid, currentRow) && checkCurrentCol(grid, currentCol)
&& checkCurrentRegion(grid, currentRow, currentCol)) {
return true;
}
return false;
}
public static boolean solvePuzzle(int[][] grid, int[][] emptyCells, int numEmptyCells) {
int i = 0;
int j = 0;
int currentCellDigit = grid[emptyCells[i][0]][emptyCells[i][1]];
while (j < numEmptyCells) {
if (currentCellDigit != 9) {
currentCellDigit++;
grid[emptyCells[i][0]][emptyCells[i][1]] = currentCellDigit;
if (isConsistent(grid, emptyCells[i][0], emptyCells[i][1])) {
grid[emptyCells[i][0]][emptyCells[i][1]] = currentCellDigit;
i++;
j++;
}
else {
grid[emptyCells[i][0]][emptyCells[i][1]] = currentCellDigit - 1;
}
}
else {
currentCellDigit = 0;
currentCellDigit = grid[emptyCells[i][0]][emptyCells[i][1]];
i--;
j--;
if (j < 0) {
return false;
}
}
}
return true;
}
public static void main(String[] args) {
final int SIZE = 9;
int[][] puzzle = { {0,2,9,0,0,3,0,0,5},
{5,0,7,0,0,0,0,9,0},
{6,0,0,0,0,9,4,2,0},
{3,0,2,0,0,4,0,0,0},
{0,0,5,0,3,0,7,0,0},
{0,0,0,5,0,0,6,0,2},
{0,9,8,4,0,0,0,0,3},
{0,3,0,0,0,0,1,0,6},
{2,0,0,3,0,0,9,4,0}
};
int[][] grid = new int[SIZE][SIZE];
int[][] emptyCellsList = new int[SIZE*SIZE][2];
int numEmptyCells = 0;
initializeGrid(grid, puzzle);
numEmptyCells = getEmptyCells(grid, emptyCellsList);
System.out.println("The puzzle:");
displayGrid(puzzle);
if (solvePuzzle(grid, emptyCellsList, numEmptyCells)) {
System.out.println("has been solved:");
displayGrid(grid);
}
else {
System.out.println("cannot be solved!");
}
}
}
答案 0 :(得分:4)
您的initializeGrid错误。恕我直言,应该是:
for (int c = 0; c < puzzle[r].length; c++)
而不是
for (int c = 0; c < puzzle[0].length; c++)
编辑:我在这下面的答案
它已被正确缩进(第1课)并相应地排列了花括号(第2课)。学会逐行理解你想要做什么,当你遇到特定的线路或方法电话时,寻求帮助(第3课)。下面的代码将编译,但不会(还)解决这个难题。阅读并替换solvePuzzle中的评论(第4课)。做一些思考和分析,因为这是你的功课;)祝你好运!
public class SudokuSolver {
public static void initializeGrid(int[][] grid, int[][] puzzle) {
for (int r = 0; r < puzzle.length; r++) {
for (int c = 0; c < puzzle[0].length; c++) {
grid [r][c] = puzzle [r][c];
}
}
}
public static void displayDigits(int r, int c, int[][] grid) {
if (grid[r][c] == 0) {
System.out.print('0');
} else {
System.out.print(grid[r][c]);
}
}
public static void displayGrid(int[][] grid) {
for (int r = 0; r < grid.length; r++) {
if (r % 3 == 0) {
System.out.println("+---+---+---+");
}
for (int c = 0; c < grid[r].length; c++) {
if (c % 3 == 0) {
System.out.print("|");
}
displayDigits(r, c, grid);
}
System.out.print("|");
System.out.println();
}
System.out.println("+---+---+---+");
}
public static int getEmptyCells(int[][] grid, int[][] emptyCells) {
int i = 0;
int numEmptyCells = 0;
for (int r = 0; r < grid.length; r++) {
for (int c = 0; c < grid[r].length; c++) {
if (grid[r][c] == 0) {
emptyCells[i][0] = r;
emptyCells[i][1] = c;
numEmptyCells++;
i++;
}
}
}
return numEmptyCells;
}
private static boolean hasNoDuplicates(int[] digitsList) {
for (int j = 0; j < digitsList.length; j++) {
for (int k = j + 1; k < digitsList.length; k++) {
if (digitsList[j] == digitsList[k] && digitsList[j] != 0)
return false;
}
}
return true;
}
private static boolean checkCurrentRow(int[][] grid, int currentRow) {
int[] digitsList = new int[grid.length];
for (int c = 0; c < digitsList.length; c++) {
digitsList[c] = grid[currentRow][c];
}
if (hasNoDuplicates(digitsList)) {
return true;
}
return false;
}
private static boolean checkCurrentCol(int[][] grid, int currentCol) {
int[] digitsList = new int[grid.length];
for (int i = 0; i < digitsList.length; i++) {
digitsList[i] = grid[i][currentCol];
}
if (hasNoDuplicates(digitsList)) {
return true;
}
return false;
}
private static boolean checkCurrentRegion(int[][] grid, int currentRow, int currentCol) {
int[] digitsList = new int[grid.length];
currentRow = (currentRow / 3) * 3;
currentCol = (currentCol / 3) * 3;
int i = 0;
for (int r = 0; r < 3; r++) {
for (int c = 0; c < 3; c++) {
digitsList[i] = grid[currentRow + r][currentCol + c];
i++;
}
}
if (hasNoDuplicates(digitsList)) {
return true;
}
return false;
}
public static boolean isConsistent(int[][] grid, int currentRow, int currentCol) {
boolean checkRow = checkCurrentRow(grid, currentRow);
boolean checkCol = checkCurrentCol(grid, currentCol);
boolean checkReg = checkCurrentRegion(grid, currentRow, currentCol);
System.out.println("r: " + checkRow + " c: " + checkCol + " r: " + checkReg);
if (checkRow && checkCol && checkReg) {
return true;
}
return false;
}
public static boolean solvePuzzle(int[][] grid, int[][] emptyCells, int numEmptyCells) {
int i = 0;
int currentCellDigit = 0;
while (i < numEmptyCells) {
if (currentCellDigit != 9) {
// increment cell value
currentCellDigit++;
// assign to current cell the current cell value
//<var> = currentCellDigit;
System.out.println("Solving---------------------- :" + currentCellDigit + " R: " + emptyCells[i][0] + " C: " + emptyCells[i][1]);
// check if value is valid
if (isConsistent(grid, emptyCells[i][0], emptyCells[i][1])) {
// reset after setting
i++;
currentCellDigit = 0;
} else {
// reset cell to zero instead of decrementing it since we're backtracking!
//grid[emptyCells[i][0]][emptyCells[i][1]] = currentCellDigit - 1;
//<var> = 0;
}
} else {
// reset current cell to 0
//<var> = 0;
// go to previous cell
i--;
// exit if theres no cell to backtrack to
if (i < 0) {
return false;
}
// set previous' cell value as current cell value
//<var> = grid[emptyCells[i][0]][emptyCells[i][1]];
}
}
return true;
}
public static void main(String[] args) {
final int SIZE = 9;
int[][] puzzle = { {0,2,9,0,0,3,0,0,5},
{5,0,7,0,0,0,0,9,0},
{6,0,0,0,0,9,4,2,0},
{3,0,2,0,0,4,0,0,0},
{0,0,5,0,3,0,7,0,0},
{0,0,0,5,0,0,6,0,2},
{0,9,8,4,0,0,0,0,3},
{0,3,0,0,0,0,1,0,6},
{2,0,0,3,0,0,9,4,0}
};
int[][] grid = new int[SIZE][SIZE];
int[][] emptyCellsList = new int[SIZE*SIZE][2];
int numEmptyCells = 0;
initializeGrid(grid, puzzle);
numEmptyCells = getEmptyCells(grid, emptyCellsList);
System.out.println("The puzzle:");
displayGrid(puzzle);
if (solvePuzzle(grid, emptyCellsList, numEmptyCells)) {
System.out.println("has been solved:");
displayGrid(grid);
} else {
System.out.println("cannot be solved!");
}
}
}
P.S。如果你用适当的代码替换上面的注释,这将做回溯。
答案 1 :(得分:0)
仔细考虑solvePuzzle
中的代码。 grid
和currentCellDigit
之间有多项冗余分配。 i
和j
中的一个是多余的,它们具有相同的值。
使用调试器来了解您的代码正在做什么。
更好的缩进会使您的代码更具可读性。
答案 2 :(得分:-1)
public static boolean solvePuzzle(int[][] grid, int[][] emptyCells,
int numEmptyCells) {
int i = 0;
int currentCellNum = 0;
while (i < numEmptyCells) {
currentCellNum = grid[emptyCells[i][0]][emptyCells[i][1]];
if (currentCellNum != 9) {
currentCellNum++;
grid[emptyCells[i][0]][emptyCells[i][1]] = currentCellNum;
if (isConsistent(grid, emptyCells[i][0], emptyCells[i][1])) {
i++;
}
} else {
currentCellNum = 0;
grid[emptyCells[i][0]][emptyCells[i][1]] = currentCellNum;
i--;
if (i < 0) {
return false;
}
}
}
return true;
}