[LeetCode] Valid Sudoku

Valid Sudoku

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.

解题思路：

题意为验证数独的有效性。这里说的有效是值谜面的有效性，不包括是否能够解出。数独的规则是，每一行1-9只出现一次，每一列1-9只出现一次，每一个小九宫格1-9只出现一次。依次验证即可。一个陷阱就是字符减的不是’0’，而是’1′

class Solution {public:bool isValidSudoku(vector<vector<char>>& board) {//验证每一行是否有效for(int i=0; i<9; i++){if(!checkRowValid(board, i)){return false;}}//验证每一列是否有效for(int i=0; i<9; i++){if(!checkColumnValid(board, i)){return false;}}//验证每一格是否有效for(int i=0; i<9; i=i+3){for(int j=0; j<9; j=j+3){if(!checkGridValid(board, i, j)){return false;}}}return true;}//验证每个格是否有效，传入的是左上角的下标bool checkGridValid(vector<vector<char>>& board, int m, int n){bool flag[9];memset(flag, 0, sizeof(bool)*9);for(int i=m; i<m+3; i++){for(int j=n; j<n+3; j++){if(board[i][j]=='.'){continue;}if(flag[board[i][j]-'1']){return false;}flag[board[i][j]-'1']=true;}}return true;}//验证每一行是否有效，，传入的是行号bool checkRowValid(vector<vector<char>>& board, int m){bool flag[9];memset(flag, 0, sizeof(bool)*9);for(int i=0; i<9; i++){if(board[m][i]=='.'){continue;}if(flag[board[m][i]-'1']){return false;}flag[board[m][i]-'1']=true;}return true;}//验证每一列是否有效，传入的是列号bool checkColumnValid(vector<vector<char>>& board, int n){bool flag[9];memset(flag, 0, sizeof(bool)*9);for(int i=0; i<9; i++){if(board[i][n]=='.'){continue;}if(flag[board[i][n]-'1']){return false;}flag[board[i][n]-'1']=true;}return true;}};

拥有一颗比九万五千公里还辽阔的心，