LeetCode 36. 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.

思路

行搜索、列搜索、sub-box搜索，根据规则来就行了

代码

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        set<char> workingSet;
        // Row
        char c;
        for(int row = 0; row<9; row++){
            workingSet.clear();
            for(int col=0; col<9; col++){
                c = board[row][col];
                if(c == '.')
                    continue;
                if(workingSet.count(c) > 0)
                    return false;
                workingSet.insert(c);
            }
        }
        // Col
        for(int col = 0; col<9; col++){
            workingSet.clear();
            for(int row=0; row<9; row++){
                c = board[row][col];
                if(c == '.')
                    continue;
                if(workingSet.count(c) > 0)
                    return false;
                workingSet.insert(c);
            }
        }
        // Sub-box
        for(int lPos=0; lPos < 9; lPos+=3){
            for(int tPos=0; tPos<9; tPos+=3){
                workingSet.clear();
                for(int i=0; i<3; i++){
                    for(int j=0; j<3; j++){
                        c = board[lPos+i][tPos+j];
                        if(c == '.')
                            continue;
                        if(workingSet.count(c) > 0)
                            return false;
                        workingSet.insert(c);
                    }
                }
            }
        }
        return true;
    }
};