Add new test - sudoku solver.

tests/sudoku_solver.aer

@@ -0,0 +1,105 @@
+import 'math';
+
+class Sudoku {
+	public int[] $board;
+	int $size;
+
+	public void __construct(int[] $board) {
+		$this->board = $board;
+		$this->size = sizeof($this->board);
+	}
+
+	public bool isSafe(int $row, int $col, int $n) {
+		for(int $d = 0; $d < $this->size; $d++) {
+			if($this->board[$row][$d] == $n) {
+				return false;
+			}
+		}
+		for(int $r = 0; $r < $this->size; $r++) {
+			if($this->board[$r][$col] == $n) {
+				return false;
+			}
+		}
+		int $sqrt = (int) sqrt($this->size);
+		int $boxRowStart = $row - $row % $sqrt;
+		int $boxColStart = $col - $col % $sqrt;
+		for(int $w = $boxRowStart; $w < $boxRowStart + $sqrt; $w++) {
+			for(int $q = $boxColStart; $q < $boxColStart + $sqrt; $q++) {
+				if($this->board[$w][$q] == $n) {
+					return false;
+				}
+			}
+		}
+		return true;
+	}
+
+	public void print() {
+		for(int $r = 0; $r < $this->size; $r++) {
+			for(int $d = 0; $d < $this->size; $d++) {
+				print($this->board[$r][$d] + " ");
+			}
+			print("\n");
+		}
+	}
+
+	public bool solve() {
+		int $row = -1;
+		int $col = -1;
+		bool $isEmpty = true;
+		for(int $i = 0; $i < $this->size; $i++) {
+			for(int $j = 0; $j < $this->size; $j++) {
+				if($this->board[$i][$j] == 0) {
+					$row = $i;
+					$col = $j;
+					$isEmpty = false;
+					break;
+				}
+			}
+			if(!$isEmpty) {
+				break;
+			}
+		}
+		if($isEmpty) {
+			return true;
+		}
+		for(int $n = 1; $n <= $this->size; $n++) {
+			if($this->isSafe($row, $col, $n)) {
+				$this->board[$row][$col] = $n;
+				if($this->solve()) {
+					return true;
+				} else {
+					$this->board[$row][$col] = 0;
+				}
+			}
+		}
+		return false;
+	}
+
+}
+
+class Program {
+
+	void main() {
+		int[] $board = {
+			{3, 0, 6, 5, 0, 8, 4, 0, 0},
+			{5, 2, 0, 0, 0, 0, 0, 0, 0},
+			{0, 8, 7, 0, 0, 0, 0, 3, 1},
+			{0, 0, 3, 0, 1, 0, 0, 8, 0},
+			{9, 0, 0, 8, 6, 3, 0, 0, 5},
+			{0, 5, 0, 0, 9, 0, 6, 0, 0},
+			{1, 3, 0, 0, 0, 0, 2, 5, 0},
+			{0, 0, 0, 0, 0, 0, 0, 7, 4},
+			{0, 0, 5, 2, 0, 6, 3, 0, 0}
+		};
+		object $sudoku = new Sudoku($board);
+		$sudoku->print();
+		print("=================\n");
+		if($sudoku->solve()) {
+			$sudoku->print();
+		} else {
+			print("No solution found\n");
+			$sudoku->print();
+		}
+	}
+
+}