Leetcode 36. Valid Sudoku (Easy) (cpp)

Leetcode 36. Valid Sudoku (Easy) (cpp)

Tag: Hash Table

Difficulty: Easy

/*36. Valid Sudoku (Easy)Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where empty cells are filled with the character '.'.A partially filled sudoku which is valid.Note:A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.*/class Solution {public:bool isValidSudoku(vector<vector<char>>& board) {for (int i = 0; i < 9; i++) {unordered_map<char, bool> mapping1;unordered_map<char, bool> mapping2;unordered_map<char, bool> mapping3;for (int j = 0; j < 9; j++) {if (board[i][j] != '.') {if (mapping1[board[i][j]] == true) {                        return false;                    } else {                        mapping1[board[i][j]] = true;                    }                                }                if (board[j][i] != '.') {                    if (mapping2[board[j][i]] == true) {                        return false;                    } else {                        mapping2[board[j][i]] = true;                    }                }                if (board[i / 3 * 3 + j / 3][i % 3 * 3 + j % 3] != '.') {                    if (mapping3[board[i / 3 * 3 + j / 3][i % 3 * 3 + j % 3]] == true) {                        return false;                    } else {                        mapping3[board[i / 3 * 3 + j / 3][i % 3 * 3 + j % 3]] = true;                    }                }            }        }        return true;    }};class Solution {public:bool isValidSudoku(vector<vector<char>>& board) {int mapping1[9][9] = {0};int mapping2[9][9] = {0};int mapping3[9][9] = {0};for (int i = 0; i < 9; i++) {for (int j = 0; j < 9; j++) {if (board[i][j] != '.') {int num = board[i][j] - '0' - 1, k = i / 3 * 3 + j / 3;if (mapping1[i][num] || mapping2[j][num] || mapping3[k][num]) {                        return false;                    }mapping1[i][num] = mapping2[j][num] = mapping3[k][num] = 1;}}}return true;}};