LeetCode 37. 解数独 困难

我的解题

#include <bits/stdc++.h>
using namespace std;

class Solution
{
    constexpr static int ROW_INDEX = 8; // 行下标
    constexpr static int COL_INDEX = 8; // 列下标
public:
    void solveSudoku(vector<vector<char>> &board)
    {
        backtrace(board, 0, 0);
    }
    void backtrace(vector<vector<char>> &board, int row, int col)
    {
        if (row >= ROW_INDEX && col >= COL_INDEX)
        {
            return;
        }
        else if (board[row][col] == '.')
        {
            for (char val = '1'; val <= '9'; ++val)
            {
                if (possible(board, row, col, val))
                {
                    board[row][col] = val;
                    auto coordinate = getNextCoordinate(row, col);
                    backtrace(board, coordinate.first, coordinate.second);
                    board[row][col] = '.';
                }
            }
        }
        else
        {
            auto coordinate = getNextCoordinate(row, col);
            backtrace(board, coordinate.first, coordinate.second);
        }
    }
    std::pair<int, int> getNextCoordinate(int row, int col)
    {
        if (col < COL_INDEX)
        {
            return
            {   row, col+1};
        }
        else
        {
            return
            {   row+1,0};
        }
    }
    /**
     * @brief
     *
     * @param row
     * @param col
     * @param val
     * @return
     */
    bool possible(vector<vector<char>> &board, int row, int col, char val)
    {
        unordered_map<int, int> count;
        // 校验行
        auto &row_data = board[row];

        for (int i = 0; i <= COL_INDEX; ++i)
        {
            if (row_data[i] != '.' && row_data[i] == val)
            {
                return false;
            }
        }
        // 校验列
        for (int i = 0; i <= ROW_INDEX; ++i)
        {
            if (board[i][col] != '.' && board[i][col] == val)
            {
                return false;
            }
        }
        // 统计3x3 宫
        int row_order = row / 3;

        int col_order = col / 3;
        for (int i = row_order * 3; i < (row_order + 1) * 3; ++i)
            for (int j = col_order * 3; j < (col_order + 1) * 3; ++i)
            {
                if (board[i][j] != '.' && board[i][j] == val)
                {
                    return false;
                }
            }
        return true;
    }

};

int main()
{

}