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.

class Solution {
    bool validate(vector<char> &num){
        vector<bool> v(10,false);
        for(int ii = 0; ii < num.size(); ++ii){
            if (num[ii] == '.') continue;
            int index = num[ii] - '0';
            if (v[index]) return false;
            else (v[index] = true);
        }
        return true;
    }
public:
    bool isValidSudoku(vector<vector<char> > &board) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        for(int ii = 0; ii < board.size(); ++ii){
            if (!validate(board[ii])) return false;
        }
        
        for(int col = 0; col < board.size(); ++col){
            vector<char> v;
            for(int row = 0; row < board.size(); ++row){
                v.push_back(board[row][col]);
            }
            if (!validate(v)) return false;
        }
        
        for(int start = 0; start < 3; ++start){
            for(int first = 0; first < 3; ++first){
                vector<char> block;
                for(int line = 0; line < 3; ++line){
                    for(int cell = 0; cell < 3; ++cell){
                        int row = start * 3 + line;
                        int col = first * 3 + cell;
                        block.push_back(board[row][col]);
                    }
                }
                if (!validate(block)) return false;
            }
        }
        return true;
    }
};