题解

#include<iostream>
using namespace std;
int mp[15][15];
bool tryFill(int x,int y,int val)
{
	//检查行
	for (int i=1;i<=9;i++)//枚举列
	{
		if (mp[x][i]==val)
		{
			return 0;
		}
	}
	//检查列
	for (int i=1;i<=9;i++)//枚举行
	{
		if (mp[i][y]==val)
		{
			return 0;
		}
	}
	//检查九宫格
	x--,y--;
	int startX=x-x%3+1,startY=y-y%3+1;
	for (int i=0;i<3;i++)
	{
		for (int j=0;j<3;j++)
		{
			if (mp[startX+i][startY+j]==val)
			{
				return 0;
			}
		}
	}
	return 1;
}
bool solve()
{
	for (int i=1;i<=9;i++)
	{
		for (int j=1;j<=9;j++)
		{
			if (mp[i][j]==0)
			{
				for (int val=1;val<=9;val++)
				{
					if (tryFill(i,j,val))
					{
						mp[i][j]=val;
						if (solve())
						{
							return 1;
						}
						mp[i][j]=0;
					}
				}
				return 0;
			}
		}
	}
	return 1;
}
int main()
{
	for (int i=1;i<=9;i++)
	{
		for (int j=1;j<=9;j++)
		{
			cin>>mp[i][j];
		}
	}
	if (solve())
	{
		for (int i=1;i<=9;i++)
		{
			for (int j=1;j<=9;j++)
			{
				cout<<mp[i][j]<<" ";
			}
			cout<<"\n";
		}
	}
	return 0;
}