diff --git a/SudokuSolver.py b/SudokuSolver.py
index 78d31eb..361d5f8 100644
--- a/SudokuSolver.py
+++ b/SudokuSolver.py
@@ -1,54 +1,44 @@
 class SudokuSolver:
     @staticmethod
     def solve(puzzle):
-        sudoku_dict = {}
-        r = 'ABCDEFGHI'
-        c = '123456789'
+        row, col = SudokuSolver.find_empty_cell(puzzle)
+        if row == -1 and col == -1:
+            return True
+
+        for num in range(1, 10):
+            if SudokuSolver.is_valid_number(puzzle, row, col, num):
+                puzzle[row][col] = num
+
+                if SudokuSolver.solve(puzzle):
+                    return True
+
+                puzzle[row][col] = 0
+
+        return False
+
+    @staticmethod
+    def find_empty_cell(grid):
         for i in range(9):
             for j in range(9):
-                sudoku_dict[r[i]+c[j]] = str(puzzle[i][j]) if puzzle[i][j] != 0 else c
-        square = [[x+y for x in i for y in j] for i in ('ABC','DEF','GHI') for j in ('123','456','789')]
-        peers = {}
-        for key in sudoku_dict.keys():
-            value = [i for i in square if key in i][0]
-            row = [[x+y for x in i for y in j][0] for i in key[0] for j in c]
-            col = [[x+y for x in i for y in j][0] for i in r for j in key[1]]
-            peers[key] = set(x for x in value+row+col if x != key)
+                if grid[i][j] == 0:
+                    return i, j
+        return -1, -1
+
+    @staticmethod
+    def is_valid_number(grid, row, col, num):
         for i in range(9):
-            sudoku_dict = SudokuSolver.Check(sudoku_dict,peers)
-        sudoku_dict = SudokuSolver.search(sudoku_dict, peers)
-        solution = []
-        for i in r:
-            solution.append([])
-            for j in c:
-                solution[r.find(i)].append(int(sudoku_dict[i+j]))
-        return solution
+            if grid[row][i] == num:
+                return False
 
-    @staticmethod
-    def Check(sudoku_dict, peers):
-        for k,v in sudoku_dict.items():
-            if len(v) == 1:
-                for s in peers[k]:
-                    sudoku_dict[s] = sudoku_dict[s].replace(v,'')
-                    if len(sudoku_dict[s])==0:
-                        return False
-        return sudoku_dict
+        for i in range(9):
+            if grid[i][col] == num:
+                return False
 
-    @staticmethod
-    def search(sudoku_dict,peers):
-        if SudokuSolver.Check(sudoku_dict,peers)==False:
-            return False
-        if all(len(sudoku_dict[s]) == 1 for s in sudoku_dict.keys()): 
-            return sudoku_dict
-        n,s = min((len(sudoku_dict[s]), s) for s in sudoku_dict.keys() if len(sudoku_dict[s]) > 1)
-        res = []
-        for value in sudoku_dict[s]:
-            new_sudoku_dict = sudoku_dict.copy()
-            new_sudoku_dict[s] = value
-            ans = SudokuSolver.search(new_sudoku_dict, peers)
-            if ans:
-                res.append(ans)
-        if len(res) > 1:
-            raise Exception("Error")
-        elif len(res) == 1:
-            return res[0]
+        box_row = row - row % 3
+        box_col = col - col % 3
+        for i in range(3):
+            for j in range(3):
+                if grid[box_row + i][box_col + j] == num:
+                    return False
+
+        return True
\ No newline at end of file
diff --git a/main.py b/main.py
index 99c5fff..805b5c9 100644
--- a/main.py
+++ b/main.py
@@ -55,13 +55,13 @@ def check_sudoku_rule(table, row, col, value):
 
 sudoku_table = create_sudoku_table()
 
-try:
-    console = Console()
-    console.print("\n[bold yellow]Solving Sudoku...[/bold yellow]")
-    start = time.process_time()
-    solved_puzzle = SudokuSolver.solve(sudoku_table)
-    in_time = time.process_time() - start
+console = Console()
+console.print("\n[bold yellow]Solving Sudoku...[/bold yellow]")
+start = time.process_time()
+status = SudokuSolver.solve(sudoku_table)
+in_time = time.process_time() - start
+if status == True:
     console.print(f"\n[bold green]Finish! in {in_time} [/bold green]")
-    print_sudoku_table(solved_puzzle, console, clear=False)
-except Exception:
+    print_sudoku_table(sudoku_table, console, clear=False)
+elif status == False:
     console.print("\n[bold red]Failed to solve![/bold red]")
diff --git a/tests/test_SudokuSolver.py b/tests/test_SudokuSolver.py
new file mode 100644
index 0000000..e797b47
--- /dev/null
+++ b/tests/test_SudokuSolver.py
@@ -0,0 +1,45 @@
+import sys
+sys.path.append('..')
+
+from SudokuSolver import SudokuSolver
+
+def test_solve_sudoku():
+    # Test a valid Sudoku grid
+    grid = [
+        [5, 3, 0, 0, 7, 0, 0, 0, 0],
+        [6, 0, 0, 1, 9, 5, 0, 0, 0],
+        [0, 9, 8, 0, 0, 0, 0, 6, 0],
+        [8, 0, 0, 0, 6, 0, 0, 0, 3],
+        [4, 0, 0, 8, 0, 3, 0, 0, 1],
+        [7, 0, 0, 0, 2, 0, 0, 0, 6],
+        [0, 6, 0, 0, 0, 0, 2, 8, 0],
+        [0, 0, 0, 4, 1, 9, 0, 0, 5],
+        [0, 0, 0, 0, 8, 0, 0, 7, 9]
+    ]
+    assert SudokuSolver.solve(grid)
+    assert is_valid_solution(grid)
+
+    # Test an invalid Sudoku grid
+    grid = [
+        [6, 3, 0, 0, 7, 0, 0, 0, 0],
+        [6, 0, 0, 1, 9, 5, 0, 0, 0],
+        [0, 9, 8, 0, 0, 0, 0, 6, 0],
+        [8, 0, 0, 0, 6, 0, 0, 0, 3],
+        [4, 0, 0, 8, 0, 3, 0, 0, 1],
+        [7, 0, 0, 0, 2, 0, 0, 0, 6],
+        [0, 6, 0, 0, 0, 0, 2, 8, 0],
+        [0, 0, 0, 4, 1, 9, 0, 0, 5],
+        [0, 0, 0, 0, 8, 0, 0, 0, 9]
+    ]
+    assert not SudokuSolver.solve(grid)
+
+def is_valid_solution(grid):
+    # Check if each row, column, and 3x3 box contains all numbers from 1 to 9
+    for i in range(9):
+        row_nums = set(grid[i])
+        col_nums = set(grid[j][i] for j in range(9))
+        box_nums = set(grid[i//3*3+j//3][i%3*3+j%3] for j in range(9))
+        if row_nums != set(range(1, 10)) or col_nums != set(range(1, 10)) or box_nums != set(range(1, 10)):
+            return False
+    return True
+