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Sudoku: Difference between revisions
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=={{header|J}}==
See [[j:Essays/Sudoku|Solving Sudoku in J]].
=={{header|Java}}==
<lang java>public class SudokuSolver {
private int[] grid;
public SudokuSolver(String s) {
grid = new int[81];
for (int i = 0; i < s.length(); i++) {
grid[i] = Character.getNumericValue(s.charAt(i));
}
}
public void solve() {
try {
placeNumber(0);
System.out.println("Unsolvable!");
} catch (Exception ex) {
System.out.println(ex.getMessage());
System.out.println(this);
}
}
public void placeNumber(int pos) throws Exception {
if (pos == 81) {
throw new Exception("Finished!");
}
if (grid[pos] > 0) {
placeNumber(pos + 1);
return;
}
for (int n = 1; n <= 9; n++) {
if (checkValidity(n, pos % 9, pos / 9)) {
grid[pos] = n;
placeNumber(pos + 1);
grid[pos] = 0;
}
}
}
public boolean checkValidity(int val, int x, int y) {
for (int i = 0; i < 9; i++) {
if (grid[y * 9 + i] == val || grid[i * 9 + x] == val)
return false;
}
int startX = (x / 3) * 3;
int startY = (y / 3) * 3;
for (int i = startY; i < startY + 3; i++) {
for (int j = startX; j < startX + 3; j++) {
if (grid[i * 9 + j] == val)
return false;
}
}
return true;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
sb.append(grid[i * 9 + j] + " ");
if (j == 2 || j == 5)
sb.append("| ");
}
sb.append('\n');
if (i == 2 || i == 5)
sb.append("------+-------+------\n");
}
return sb.toString();
}
public static void main(String[] args) {
new SudokuSolver("850002400" +
"720000009" +
"004000000" +
"000107002" +
"305000900" +
"040000000" +
"000080070" +
"017000000" +
"000036040").solve();
}
}</lang>
=={{header|OCaml}}==
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