leetcode—sudoku solver

最新推荐文章于 2025-09-12 17:31:31 发布

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最新推荐文章于 2025-09-12 17:31:31 发布

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CC 4.0 BY-SA版权

文章标签：数据结构与算法

原文链接：http://www.cnblogs.com/obama/p/3329649.html

本文介绍了一种使用C++实现的数独求解算法。通过递归回溯的方式填充空缺单元格，并验证每一步填充是否合法来确保最终解的唯一性和正确性。

1.题目描述

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.

2.解法分析

class Solution
{
public:
bool isValid(vector<vector<char> > &board, int x, int y)
    {
int i, j;
for (i = 0; i < 9; i++)
if (i != x && board[i][y] == board[x][y])
return false;
for (j = 0; j < 9; j++)
if (j != y && board[x][j] == board[x][y])
return false;
for (i = 3 * (x / 3); i < 3 * (x / 3 + 1); i++)
for (j = 3 * (y / 3); j < 3 * (y / 3 + 1); j++)
if (i != x && j != y && board[i][j] == board[x][y])
return false;
return true;
    }

bool solveSudoku(vector<vector<char>> &board)
    {
for(int y=0;y<9;++y)
        {
for(int x=0;x<9;++x)
            {
if(board[y][x]=='.')
                {
for(int i=1;i<=9;++i)
                    {
                        board[y][x]='0'+i;
if(isValid(board,y,x))
                        {
// if(x==8)if(mySolveSudoku(board,sh+1))return true;
if(solveSudoku(board))return true;
                        }

                        board[y][x]='.';
                    }

return false;
                }
            }
        }

return true;
    }
};