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.

注意：其中没有填的也代表有效的，用'.'表示。为了是每行每列以及每个9方格中没有重复的元素，使用了set来存放，本来想用map的，但是map每次要存放两个元素，多余。

当每行或每列填满之后，可以直接判断set的长度是否为9，否则就是有重复的元素。

 

C++代码如下：

#include<iostream>

#include<set>

#include<vector>

using namespace std;



class Solution

{

public:

    bool isValidSudoku(vector<vector<char> > &board)

    {

        set<char> st;

        size_t dot=0;

        int i,j;

        for(i=0; i<9; i++)

        {

            st.clear();

            dot=0;

            for(j=0; j<9; j++)

            {

                if(board[i][j]=='.')

                {

                    dot++;

                    continue;

                }

                st.insert(board[i][j]);

            }

            if(st.size()<9-dot)

                return false;

        }

        for(i=0; i<9; i++)

        {

            st.clear();

            dot=0;

            for(j=0; j<9; j++)

            {

                if(board[j][i]=='.')

                {

                    dot++;

                    continue;

                }

                st.insert(board[j][i]);

            }

            if(st.size()<9-dot)

                return false;

        }

        int block=0;

        for(block=0; block<9; block++)

        {

            dot=0;

            st.clear();

            for(i=block/3*3; i<block/3*3+3; i++)

            {

                for(j=block%3*3; j<block%3*3+3; j++)

                {

                    if(board[i][j]=='.')

                    {

                        dot++;

                        continue;

                    }

                    st.insert(board[i][j]);

                }

            }

            if(st.size()<9-dot)

                return false;

        }

        return true;

    }

};



int main()

{

    Solution s;

    /*vector<vector<char> > vec= {{'8','1','4','6','5','2','7','3','9'},

        {'9','5','7','1','8','3','6','2','4'},

        {'2','3','6','9','7','4','1','5','8'},

        {'6','9','5','4','3','7','2','8','1'},

        {'4','8','1','5','2','6','3','9','7'},

        {'3','7','2','8','9','1','5','4','6'},

        {'5','6','9','3','1','8','4','7','2'},

        {'7','4','8','2','6','5','9','1','3'},

        {'1','2','3','7','4','9','8','6','5'}

    };*/

    vector<vector<char> >vec= {{'.','.','5','.','.','.','.','.','6'},

        {'.','.','.','.','1','4','.','.','.'},

        {'2','.','.','.','.','.','.','.','.'},

        {'1','.','.','.','.','.','.','.','.'},

        {'5','.','.','.','.','.','.','.','.'},

        {'6','.','.','.','.','.','.','.','.'},

        {'7','.','.','.','.','.','.','.','.'},

        {'8','.','.','.','.','.','.','.','.'},

        {'9','.','.','.','.','.','.','.','.'},

    };

    cout<<s.isValidSudoku(vec)<<endl;

}