我一直在搜索数独求解算法，我找到了这段代码。但我有一些困难。我无法理解。如果在单个单元格中存在1到9之间的所有数字冲突，程序应该停止，对吧？但它仍在继续。有人可以解释一下代码是如何工作的吗？这是：
bool Sudoku::Help_Solve(int i, int j)
{
int nextrow, nextcol;
while(change[i][j] == 1) //We find the first cell in which we can change the number
{
j++;
if(j > 9)
{
j = 1;
i++;
}
if(i > 9) return true;
}
for(int p = 1; p <= 9; p++)
{
if(Game.Check_Conflicts(p, i, j)) //We are checking for conflicts
{
board[i][j] = p;
nextrow = i;
nextcol = j+1;
if(nextcol > 9)
{
nextcol = 1;
nextrow++;
}
if(nextcol == 1 && nextrow == 10) return true;
if(Game.Help_Solve(nextrow, nextcol)) return true;
}
}
board[i][j] = 0;
return false;
}
答案 0 :(得分：0)
没有足够的代码来正确解释，Game.Check_Conflicts（p，i，j）中会发生什么，这个函数是否会被递归调用？
答案 1 :(得分：0)
如果你想看到它，这是整个代码：
#include <iostream>
#include <iomanip>
#include <time.h>
#include <cstdlib>
#include <windows.h>
using namespace std;
class Sudoku
{
private:
int board[9][9];
int change[9][9];
public:
Sudoku();
void Print_Board();
void Add_First_Cord();
bool Help_Solve(int i, int j);
bool Check_Conflicts(int p, int i, int j);
};
Sudoku Game;
void setcolor(unsigned short color) //The function that you'll use to
{ //set the colour
HANDLE hcon = GetStdHandle(STD_OUTPUT_HANDLE);
SetConsoleTextAttribute(hcon,color);
}
Sudoku::Sudoku()
{
for(int i = 0; i <= 9; i++)
for(int j = 0; j <= 9; j++)
board[i][j] = 0;
}
void Sudoku::Print_Board()
{
for(int i = 1; i <= 9; i++)
{
for(int j = 1; j <= 9; j++)
{
if(change[i][j] == 1)
{
setcolor(12);
cout << board[i][j] << " ";
setcolor(7);
}
else cout << board[i][j] << " ";
if(j%3 == 0) cout << "| ";
}
cout << endl;
if(i%3 == 0) cout << "------+-------+--------" << endl;
}
}
void Sudoku::Add_First_Cord()
{
board[1][1] = 5; change[1][1] = 1;
board[1][2] = 3; change[1][2] = 1;
board[1][5] = 7; change[1][5] = 1;
board[2][1] = 6; change[2][1] = 1;
board[2][4] = 1; change[2][4] = 1;
board[2][5] = 9; change[2][5] = 1;
board[2][6] = 5; change[2][6] = 1;
board[3][2] = 9; change[3][2] = 1;
board[3][3] = 8; change[3][3] = 1;
board[3][8] = 6; change[3][8] = 1;
board[4][1] = 8; change[4][1] = 1;
board[4][5] = 6; change[4][5] = 1;
board[4][9] = 3; change[4][9] = 1;
board[5][1] = 4; change[5][1] = 1;
board[5][4] = 8; change[5][4] = 1;
board[5][6] = 3; change[5][6] = 1;
board[5][9] = 1; change[5][9] = 1;
board[6][1] = 7; change[6][1] = 1;
board[6][5] = 2; change[6][5] = 1;
board[6][9] = 6; change[6][9] = 1;
board[7][2] = 6; change[7][2] = 1;
board[7][7] = 2; change[7][7] = 1;
board[7][8] = 8; change[7][8] = 1;
board[8][4] = 4; change[8][4] = 1;
board[8][5] = 1; change[8][5] = 1;
board[8][6] = 9; change[8][6] = 1;
board[8][9] = 5; change[8][9] = 1;
board[9][5] = 8; change[9][5] = 1;
board[9][8] = 7; change[9][8] = 1;
board[9][9] = 9; change[9][9] = 1;
}
bool Sudoku::Check_Conflicts(int p, int i, int j)
{
for(int k = 1; k <= 9; k++)
if(board[i][k] == p) return false;
for(int q = 1; q <= 9; q++)
if(board[q][j] == p) return false;
/*
*00
000
000
*/
if((j == 1 || j == 4 || j == 7) && (i == 1 || i == 4 || i == 7))
{
if(board[i][j+1] == p || board[i][j+2] == p || board[i+1][j] == p ||
board[i+2][j] == p || board[i+1][j+1] == p || board[i+1][j+2] == p ||
board[i+2][j+1] == p || board[i+2][j+2] == p)return false;
}
/*
000
000
*00
*/
if((j == 1 || j == 4 || j == 7) && (i == 3 || i == 6 || i == 9))
{
if(board[i-1][j] == p || board[i-2][j] == p || board[i][j+1] == p ||
board[i][j+2] == p || board[i-1][j+1] == p || board[i-1][j+2] == p ||
board[i-2][j+1] == p || board[i-2][j+2] == p)return false;
}
/*
000
*00
000
*/
if((j == 1 || j == 4 || j == 7) && (i == 2 || i == 5 || i == 8))
{
if(board[i-1][j] == p || board[i-1][j+1] == p || board[i-1][j+2] == p ||
board[i][j+1] == p || board[i][j+2] == p || board[i+1][j] == p ||
board[i+1][j+1] == p || board[i+1][j+2] == p)return false;
}
/*
0*0
000
000
*/
if((j == 2 || j == 5 || j == 8) && (i == 1 || i == 4 || i == 7))
{
if(board[i][j-1] == p || board[i][j+1] == p || board[i+1][j+1] == p ||
board[i+1][j-1] == p || board[i+1][j] == p || board[i+2][j-1] == p ||
board[i+2][j] == p || board[i+2][j+1] == p)return false;
}
/*
000
0*0
000
*/
if((j == 2 || j == 5 || j == 8) && (i == 2 || i == 5 || i == 8))
{
if(board[i-1][j] == p || board[i-1][j-1] == p || board[i-1][j+1] == p ||
board[i][j+1] == p || board[i][j-1] == p || board[i+1][j+1] == p ||
board[i+1][j] == p || board[i+1][j-1] == p)return false;
}
/*
000
000
0*0
*/
if((j == 2 || j == 5 || j == 8) && (i == 3 || i == 6 || i == 9))
{
if(board[i][j-1] == p || board[i][j+1] == p || board[i-1][j] == p ||
board[i-1][j+1] == p || board[i-1][j-1] == p || board[i-2][j] == p ||
board[i-2][j+1] == p || board[i-2][j-1] == p) return false;
}
/*
00*
000
000
*/
if((j == 3 || j == 6 || j == 9) && (i == 1 || i == 4 || i == 7))
{
if(board[i][j-1] == p || board[i][j-2] == p || board[i+1][j] == p ||
board[i+1][j-1] == p || board[i+1][j-2] == p || board[i+2][j] == p ||
board[i+2][j-1] == p || board[i+2][j-2] == p) return false;
}
/*
000
00*
000
*/
if((j == 3 || j == 6 || j == 9) && (i == 2 || i == 5 || i == 8))
{
if(board[i-1][j] == p || board[i-1][j-1] == p || board[i-1][j-2] == p ||
board[i][j-1] == p || board[i][j-2] == p || board[i+1][j] == p ||
board[i+1][j-1] == p || board[i+1][j-2] == p) return false;
}
/*
000
000
00*
*/
if((j == 3 || j == 6 || j == 9) && (i == 3 || i == 6 || i == 9))
{
if(board[i][j-1] == p || board[i][j-2] == p || board[i-1][j] == p ||
board[i-1][j-1] == p || board[i-1][j-2] == p || board[i-2][j] == p ||
board[i-2][j-1] == p || board[i-2][j-2] == p) return false;
}
return true;
}
bool Sudoku::Help_Solve(int i, int j)
{
int nextrow, nextcol;
while(change[i][j] == 1)
{
j++;
if(j > 9)
{
j = 1;
i++;
}
if(i > 9) return true;
}
for(int p = 1; p <= 9; p++)
{
if(Game.Check_Conflicts(p, i, j))
{
board[i][j] = p;
nextrow = i;
nextcol = j+1;
if(nextcol > 9)
{
nextcol = 1;
nextrow++;
}
if(nextcol == 1 && nextrow == 10) return true;
if(Game.Help_Solve(nextrow, nextcol)) return true;
}
}
board[i][j] = 0;
return false;
}
int main()
{
Game.Add_First_Cord();
Game.Help_Solve(1, 1);
Game.Print_Board();
system("pause");
return 0;
}
答案 2 :(得分：0)
如果号码可以放在那里，Sudoku::Check_Conflicts会返回true，如果因为简单的冲突而无法放置false，则会{{1}}。一个不同的函数名称可以更好地自我记录代码。
答案 3 :(得分：0)
事情是我无法理解为什么它最终会持续下去 返回false：/
它并不总是在函数的底部返回'：
bool Sudoku::Help_Solve(int i, int j)
{
int nextrow, nextcol;
while(change[i][j] == 1) //We find the first cell in which we can change the number
{
j++;
if(j > 9)
{
j = 1;
i++;
}
if(i > 9) return true;
-------------------------^^^^
returns true if we have filled all squares.
}
for(int p = 1; p <= 9; p++)
{
if(Game.Check_Conflicts(p, i, j)) //We are checking for conflicts
{
board[i][j] = p;
nextrow = i;
nextcol = j+1;
if(nextcol > 9)
{
nextcol = 1;
nextrow++;
}
if(nextcol == 1 && nextrow == 10) return true;
-----------------------------------------------------^^^^
returns when we have filled everything!
if(Game.Help_Solve(nextrow, nextcol)) return true;
---------------------------------------------------------^^^^
returns if we filled at the next level of solution.
}
}
board[i][j] = 0;
return false;
-----------^^^^^ returns if we failed to fill the whole thing.
}
正如评论中提到的那样，有一些微不足道的事情可以用来改进算法 - 例如寻找“最适合填充的地方”[这并没有改善最坏的情况，但是它确实改善了典型案例]。
我编写了一个使用类似算法的数独求解器，但它试图找到候选者数量最少的单元格（该单元格中可能包含的数字），并且只有在有多个选项时才会递归尝试。