[LeetCode]037-Sudoku Solver

来源：互联网发布：电脑翻墙软件编辑：程序博客网时间：2024/05/22 15:58

题目：
Write a program to solve a Sudoku puzzle by filling the empty cells.

Empty cells are indicated by the character ‘.’.

You may assume that there will be only one unique solution.

Solution:
思路，类似于回溯法，层层遍历，直到最后，返回true,否则返回false。
回溯法要注意判断函数，即check，判断当前要插入的值在横向、纵向、子方格内都是合法的。

代码如下：

 void solveSudoku(vector<vector<char>>& board)     {        solve(board);    }    bool solve(vector<vector<char>>& board)    {        for(int i =0;i<9;i++)        {            for(int j = 0;j<9;j++)            {                if(board[i][j] == '.')                {                    for(int k = 1;k<=9;k++)                    {                        board[i][j] = k + '0';                        if(isValid(board,i,j) && solve(board))                            return true;                        board[i][j] = '.';                    }                    return false;                }            }        }        return true;    }    bool isValid(vector<vector<char>>& board,int row,int col)    {        int i,j;        i = j = 0;        for(i =0;i<9;i++)        {            if(i != row && board[row][col] == board[i][col])                return false;        }        for(j = 0;j<9;j++)        {            if(j != col && board[row][col] == board[row][j])                return false;        }        int grid_row = row/3 * 3;        int grid_col  = col/3 * 3;        for(i =0;i<3;i++)            for(j =0;j<3;j++)            {                if(row != i+grid_row && col != j + grid_col && board[i+grid_row][j+grid_col] == board[row][col])                    return false;            }        return true;    }

参考到一个比较简略关键思路清晰的算法：
http://blog.csdn.net/aivin24/article/details/33346657

0 0