36. Valid Sudoku
Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:
Each row must contain the digits 1-9 without repetition. Each column must contain the digits 1-9 without repetition. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition. Note:
A Sudoku board (partially filled) could be valid but is not necessarily solvable. Only the filled cells need to be validated according to the mentioned rules.
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Example 1:
Input: board =
[["5","3",".",".","7",".",".",".","."]
,["6",".",".","1","9","5",".",".","."]
,[".","9","8",".",".",".",".","6","."]
,["8",".",".",".","6",".",".",".","3"]
,["4",".",".","8",".","3",".",".","1"]
,["7",".",".",".","2",".",".",".","6"]
,[".","6",".",".",".",".","2","8","."]
,[".",".",".","4","1","9",".",".","5"]
,[".",".",".",".","8",".",".","7","9"]]
Output: true
Example 2:
Input: board =
[["8","3",".",".","7",".",".",".","."]
,["6",".",".","1","9","5",".",".","."]
,[".","9","8",".",".",".",".","6","."]
,["8",".",".",".","6",".",".",".","3"]
,["4",".",".","8",".","3",".",".","1"]
,["7",".",".",".","2",".",".",".","6"]
,[".","6",".",".",".",".","2","8","."]
,[".",".",".","4","1","9",".",".","5"]
,[".",".",".",".","8",".",".","7","9"]]
Output: false
Explanation: Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.
Constraints:
board.length == 9
board[i].length == 9
board[i][j] is a digit 1-9 or '.'.
Solution
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bool isValidNums(const vector<char>& input) {
int len = input.size();
set<char> tmp;
for (auto item : input) {
tmp.insert(item);
}
return len == tmp.size();
}
bool isValidSudoku(vector<vector<char>>& board) {
int rowLen = board.size();
int colLen = board[0].size();
for (int i = 0; i < rowLen; i++) {
vector<char> tmp;
for (int j = 0; j < colLen; j++) {
if (isdigit(board[i][j])) {
tmp.push_back(board[i][j]);
}
}
if (!isValidNums(tmp)) {
return false;
}
}
for (int i = 0; i < colLen; i++) {
vector<char> tmp;
for (int j = 0; j < rowLen; j++) {
if (isdigit(board[j][i])) {
tmp.push_back(board[j][i]);
}
}
if (!isValidNums(tmp)) {
return false;
}
}
for (int i = 0; i < rowLen; i += 3) {
for (int j = 0; j < colLen; j += 3) {
vector<char> tmp;
for (int x = 0; x < 3; x++) {
for (int y = 0; y < 3; y++) {
if (isdigit(board[i + x][j + y])) {
tmp.push_back(board[i + x][j + y]);
}
}
}
if (!isValidNums(tmp)) {
return false;
}
}
}
return true;
}
