我编写了使用回溯方法从Java中的空白网格生成数独的代码。但是我在运行程序时没有输出
public class SodokuGenerator {
int[][] puzzle=new int[9][9];
int num_givens=0;
public static int get_random_value(int high, int low)
{
//Returns a random value between the given maximum and minimum values(both inclusive)
Random r=new Random();
return (r.nextInt(high+1-low) + low);
}
public boolean check_column(int x, int y, int curr_value)
{
for (int i=0;i<9;i++)
{
if (this.puzzle[i][y]==curr_value)
{
return false;
}
}
return true;
}
public boolean check_row(int x, int y, int curr_value)
{
for (int j=0;j<9;j++)
{
if (this.puzzle[x][j]==curr_value)
{
return false;
}
}
return true;
}
public boolean check_block(int x, int y, int curr_value)
{
int block_row_start=0, block_row_end=0,block_col_start=0, block_col_end=0;
if (x==0 || x==3 || x==6)
{
block_row_start=x;
block_row_end=x+3-1;
}
else if (x==2 || x==5 || x==8)//At the end of a block
{
block_row_start=x-3+1; //both bounds are inclusive
block_row_end=x;
}
else if (x==1 || x==4 || x==7) //Neither multiples of 2 nor 3.
{
block_row_start=x-1;
block_row_end=x+1;
}
if (y==0 || y==3 || y==6)
{
block_col_start=y;
block_col_end=y+3-1;
}
else if (y==2 || y==5 || y==8)//At the end of a block
{
block_col_start=y-3+1; //both bounds are inclusive
block_col_end=y;
}
else if (y==1 || y==4 || y==7) //Neither multiples of 2 nor 3.
{
block_col_start=y-1;
block_col_end=y+1;
}
//Established the bounds of the block based on the current position
//System.out.println("block_row_start="+block_row_start);
//System.out.println("block_row_end= "+block_row_end);
for (int i=block_row_start;i<=block_row_end;i++)
{
for (int j=block_col_start;j<=block_col_end;j++)
{
//System.out.println("i="+i);
//System.out.println("j="+j);
if (this.puzzle[i][j]==curr_value)
{
return false;
}
}
}
return true;
}
public void create_puzzle()
{
int curr_value=0;
int index=0;
int[] possible_values={1,2,3,4,5,6,7,8,9};
this.puzzle[0][0]=get_random_value(9,1);
int x=0,y=1; //Holds the coordinates of the current position in the puzzle
while (x<=8 && y<=8)
{
this.puzzle[x][y]=0;
curr_value= get_random_value(9,1);
if (this.check_block(x,y, curr_value) && this.check_row(x,y,curr_value)
&& this.check_column(x,y,curr_value))
{
this.puzzle[x][y]=curr_value;
}
else //If there is a conflict with another element
{
index=-1;
//Checks for a conflict using all possible values
do //Using a do-while loop prevents a repeated computation
{
index++;
curr_value=possible_values[index];
}
while (index<8 && (this.check_block(x,y, curr_value)==false ||
this.check_row(x,y,curr_value)==false
|| this.check_column(x,y,curr_value)==false));
if (index==8)//This means that no possible solution was found
{
//BACKTRACKING
if (y==0 && x!=0)
{
y=8;
x--;
}
else
{
y--;
}
continue;
}
else //If a possible solution was found
{
this.puzzle[x][y]=curr_value;
}
}
//Advancing the current position coordinates to the next position
if (y==8)
{
y=0;
x++;
}
else
{
y++;
}
}
}
我确实在这个论坛上看过类似的问题,但是他们并没有真正帮助我。调试告诉我,游戏中存在无限循环。有谁能请我指出正确的方向?我非常感激。谢谢。
答案 0 :(得分:0)
while(x <= 8&amp; y&lt; = 8)
那个循环是无限的。尝试将值打印到循环内的屏幕。
System.out.println(“X:”+ x +“”+ y);
我没有深入检查你的代码......但我怀疑问题出现在这里:
if (index==8)//This means that no possible solution was found
{
//BACKTRACKING
if (y==0 && x!=0)
{
y=8;
x--;
}
else
{
y--;
}
continue;
}
和
if (y==8) //This if statement only runs once. Y always gets subtracted back to 7 in the code above.
{
y=0;
x++;
}
else
{
y++;
}
}
一旦索引达到8,该函数将进入else,将y减去1。之后y加一。这个过程反弹和反弹,导致y值在无限循环中为-1和+1。