Add arrays/sudoku_solver.py

data_structures/arrays/sudoku_solver.py

@@ -0,0 +1,41 @@
+class Solution:
+    def solveSudoku(self, board: List[List[str]]) -> None:
+        n = 9
+
+        def isValid(row, col, ch):
+            row, col = int(row), int(col)
+
+            for i in range(9):
+                if board[i][col] == ch:
+                    return False
+                if board[row][i] == ch:
+                    return False
+
+                if board[3 * (row // 3) + i // 3][3 * (col // 3) + i % 3] == ch:
+                    return False
+
+            return True
+
+        def solve(row, col):
+            if row == n:
+                return True
+            if col == n:
+                return solve(row + 1, 0)
+
+            if board[row][col] == ".":
+                for i in range(1, 10):
+                    if isValid(row, col, str(i)):
+                        board[row][col] = str(i)
+
+                        if solve(row, col + 1):
+                            return True
+                        else:
+                            board[row][col] = "."
+                return False
+            else:
+                return solve(row, col + 1)
+
+        solve(0, 0)
+
+
+# do upvote if it helps.