In the Valid Sodoku problem, we are given a 9×9 sudoku board, our goal is to check whether it is valid or not.<\/strong> The objective is to ensure that each row, column, and 3×3 sub-grid contains all the digits from 1 to 9 without repetition. <\/p>\n\n\n\n A valid sudoku must follow the 3 following conditions:<\/p>\n\n\n\n We have to consider only the filled value in the grid to check the validity.<\/p>\n\n\n\n Let us understand it with an example with this board:<\/p>\n\n\n Here are 9 subgrids of 3×3.<\/p>\n\n\n\n Because there is no repetition within rows, columns, and subgrids<\/p>\n\n\n\n To solve this problem, we will use a HashSet to check the repetition of numbers within rows, columns, and subgrids.<\/p>\n\n\n Below is the C++ program to solve the Valid Sudoku problem:<\/p>\n\n\n\n The implementation is quite similar in Java:<\/p>\n\n\n\n Here is the Python program as well:<\/p>\n\n\n\n Output:<\/strong><\/p>\n\n\n\n\n
![\"Example](\"https:\/\/favtutor.com\/articles\/wp-content\/uploads\/2023\/12\/Untitled-2023-11-07-1458-1-1024x560.png\")
<\/figure>\n<\/div>\n\n\nOutput = valid <\/code><\/pre>\n\n\n\nHashSet to Check Sudoku Configuration is Valid<\/strong><\/h2>\n\n\n\n
![\"subgrid](\"https:\/\/favtutor.com\/articles\/wp-content\/uploads\/2023\/12\/2-7-1024x400.png\")
<\/figure>\n<\/div>\n\n\n\n
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![\"sudoku](\"https:\/\/favtutor.com\/articles\/wp-content\/uploads\/2023\/12\/3-8-1024x400.png\")
<\/figure>\n<\/div>\n\n\n\n
C++ Code<\/strong><\/h3>\n\n\n\n
#include <bits\/stdc++.h>\nusing namespace std;\n\nclass Solution {\npublic:\n bool isValidSudoku(vector<vector<char>>& board) {\n unordered_set<string> seen;\n for (int i = 0; i < 9; i++) {\n for (int j = 0; j < 9; j++) {\n if (board[i][j] != '.') {\n if (!seen.insert("row" + to_string(i) + board[i][j]).second ||\n !seen.insert("col" + to_string(j) + board[i][j]).second ||\n !seen.insert("box" + to_string((i \/ 3) * 3 + j \/ 3) + board[i][j]).second) {\n return false;\n }\n }\n }\n }\n return true;\n }\n};\n\nint main() {\n \/\/ Example usage:\n Solution solution;\n vector<vector<char>> board = {\n {'.', '2', '.', '4', '5', '6', '.', '8', '9'},\n {'4', '.', '6', '7', '8', '9', '1', '.', '3'},\n {'7', '8', '.', '1', '.', '3', '4', '5', '6'},\n {'2', '3', '4', '5', '6', '.', '8', '9', '1'},\n {'5', '6', '7', '8', '9', '1', '.', '3', '4'},\n {'8', '.', '1', '2', '3', '4', '5', '6', '7'},\n {'3', '4', '5', '6', '.', '8', '.', '1', '2'},\n {'6', '7', '8', '9', '1', '.', '3', '.', '5'},\n {'9', '1', '.', '3', '4', '5', '6', '7', '.'}\n};\n\n bool result = solution.isValidSudoku(board);\n cout << (result ? "Valid" : "Invalid") << endl;\n\n return 0;\n}<\/pre><\/div>\n\n\n\nJava Code<\/strong><\/h3>\n\n\n\n
import java.util.HashSet;\n\nclass Solution {\n public boolean isValidSudoku(char[][] board) {\n HashSet<String> seen = new HashSet<>();\n for (int i = 0; i < 9; i++) {\n for (int j = 0; j < 9; j++) {\n if (board[i][j] != '.') {\n if (!seen.add("row" + i + board[i][j]) ||\n !seen.add("col" + j + board[i][j]) ||\n !seen.add("box" + (i \/ 3) * 3 + j \/ 3 + board[i][j])) {\n return false;\n }\n }\n }\n }\n return true;\n }\n\n public static void main(String[] args) {\n Solution solution = new Solution();\n char[][] board = {\n {'.', '2', '.', '4', '5', '6', '.', '8', '9'},\n {'4', '.', '6', '7', '8', '9', '1', '.', '3'},\n {'7', '8', '.', '1', '.', '3', '4', '5', '6'},\n {'2', '3', '4', '5', '6', '.', '8', '9', '1'},\n {'5', '6', '7', '8', '9', '1', '.', '3', '4'},\n {'8', '.', '1', '2', '3', '4', '5', '6', '7'},\n {'3', '4', '5', '6', '.', '8', '.', '1', '2'},\n {'6', '7', '8', '9', '1', '.', '3', '.', '5'},\n {'9', '1', '.', '3', '4', '5', '6', '7', '.'}\n };\n\n boolean result = solution.isValidSudoku(board);\n System.out.println(result ? "Valid" : "Invalid");\n }\n}<\/pre><\/div>\n\n\n\nPython Code<\/strong><\/h3>\n\n\n\n
from typing import List\n\nclass Solution:\n def isValidSudoku(self, board: List[List[str]]) -> bool:\n seen = set()\n for i in range(9):\n for j in range(9):\n if board[i][j] != '.':\n if f"row{i}{board[i][j]}" in seen or \\\n f"col{j}{board[i][j]}" in seen or \\\n f"box{(i \/\/ 3) * 3 + j \/\/ 3}{board[i][j]}" in seen:\n return False\n seen.add(f"row{i}{board[i][j]}")\n seen.add(f"col{j}{board[i][j]}")\n seen.add(f"box{(i \/\/ 3) * 3 + j \/\/ 3}{board[i][j]}")\n return True\n\n# Example usage\nsolution = Solution()\nboard = [\n ['.', '2', '.', '4', '5', '6', '.', '8', '9'],\n ['4', '.', '6', '7', '8', '9', '1', '.', '3'],\n ['7', '8', '.', '1', '.', '3', '4', '5', '6'],\n ['2', '3', '4', '5', '6', '.', '8', '9', '1'],\n ['5', '6', '7', '8', '9', '1', '.', '3', '4'],\n ['8', '.', '1', '2', '3', '4', '5', '6', '7'],\n ['3', '4', '5', '6', '.', '8', '.', '1', '2'],\n ['6', '7', '8', '9', '1', '.', '3', '.', '5'],\n ['9', '1', '.', '3', '4', '5', '6', '7', '.']\n]\n\nresult = solution.isValidSudoku(board)\nprint("Valid" if result else "Invalid")<\/pre><\/div>\n\n\n\nValid<\/code><\/pre>\n\n\n\n