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108 lines (85 loc) · 2.07 KB
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package leetcode;
import java.util.ArrayList;
import java.util.List;
public class SudokuSolver {
public void solveSudoku(char[][] board) {
int[][] Iboard = new int[9][9];
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
Iboard[i][j] = board[i][j] == '.' ? -1
: (board[i][j] - '0') - 1;
}
}
checkOneByOne(0, Iboard);
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
board[i][j] = (char) ('0' + (Iboard[i][j] + 1));
System.out.print(board[i][j] + " ");
}
System.out.println();
}
}
boolean checkOneByOne(int index, int[][] board) {
int x = 0, y = 0;
for (; index < 81; index++) {
if (board[index / 9][index % 9] == -1) {
x = index / 9;
y = index % 9;
break;
}
}
if (index == 81)
return true;
List<Integer> candidates = validNum(board, x, y);
if (candidates == null || candidates.size() == 0) {
return false;
}
for (int candidate : candidates) {
board[x][y] = candidate;
if (checkOneByOne(index, board)) {
return true;
}
}
board[x][y] = -1;
return false;
}
List<Integer> validNum(int[][] board, int x, int y) {
int[] valid = new int[9];
for (int i = 0; i < 9; i++) {
if (board[x][i] != -1) {
valid[board[x][i]] = 1;
}
if (board[i][y] != -1) {
valid[board[i][y]] = 1;
}
}
int x_d = x / 3;
int y_d = y / 3;
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
if (board[x_d * 3 + i][y_d * 3 + j] != -1) {
valid[board[x_d * 3 + i][y_d * 3 + j]] = 1;
}
}
}
ArrayList<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < valid.length; i++) {
if (valid[i] == 0) {
list.add(i);
}
}
return list;
}
public static void main(String[] args) {
char[][] board = new char[9][9];
String[] str = new String[] { "7269.4.51", ".8.6.7432", "341.85..9",
".52468..7", ".37...68.", ".9...3.1.", ".........",
"9...215..", "8..3....." };
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
board[i][j] = str[i].charAt(j);
}
}
new SudokuSolver().solveSudoku(board);
}
}