Java using backtracking method to solve Sudoku example _java

Copy Code code as follows:

Import Java.util.Calendar;
Import Java.util.Date;

public class Matrix {

private int matrix[][];
Private long timeafter=0;
Private long Timebefore = 0;
Public Matrix (int m[][]) {
Matrix = new Int[9][9];
for (int i=0; i<9; i++)
for (int j= 0; j<9; j + +)
MATRIX[I][J]=M[I][J];
This.timebefore = Calendar.getinstance (). Gettimeinmillis ();
}
public void BackTrack (int i, int j)
{
Reclaim System memory Resources
System.GC ();
if (i==8 && j>=9)
{
This.timeafter = Calendar.getinstance (). Gettimeinmillis ();
Successful output matrix
This.showmatrix ();
Return
}

if (j = = 9) {j = 0; i++;}

if (matrix[i][j] = = 0)
{
Number is zero
for (int k=1; k<=9; k++)
{
if (bound (i,j,k))
{
MATRIX[I][J] = k;
Match the criteria to find the next square
BackTrack (i,j+1);
MATRIX[I][J] = 0;
}
}
}else
{
Number is not zero, directly find the next
BackTrack (i, j+1);
}
}
/**
* To determine whether the numbers to be filled and the number of peers and figures in the same 19 house are duplicated
*/
Private Boolean bound (int i, int j, int k) {
int m = I/3;
int n = J/3;
for (int p = 0; p<9; p++)
{
if (k = = Matrix[i][p])
{
return false;
}
if (k = = Matrix[p][j])
{
return false;
}
if (k = = matrix[3*m+p/3][3*n+p%3])
{
return false;
}
}
return true;
}
/**
* Print Solution Time
* @return
*/
Public long Printtime ()
{
return this.timeafter-this.timebefore;
}
/**
* Print Matrix
*/
public void Showmatrix ()
{
for (int i=0; i<9; i++)
{
for (int j=0; j<9; j + +)
{
System.out.print (matrix[i][j]+ "");
}
System.out.println ();
}
System.out.println ();
SYSTEM.OUT.PRINTLN ("Solution Time:" +printtime () + "millisecond");
System.out.println ();
}
public static void Main (string[] args) {
int matrix[][] = {
{3,0,6,0,5,7,0,0,0},
{7,9,0,0,2,4,0,0,0},
{0,5,0,6,0,0,9,7,4},
{8,0,1,0,0,9,0,0,0},
{0,2,0,3,0,8,0,0,7},
{4,0,0,0,6,0,5,0,0},
{0,0,4,0,3,6,0,5,0},
{2,0,3,7,0,5,0,0,1},
{0,0,7,4,1,0,6,0,0}};

int ma1[][]={
{0,3,0,0,0,5,0,6,0},
{0,1,0,0,0,3,0,8,0},
{0,4,0,0,0,0,0,0,7},
{0,0,7,0,2,4,0,0,0},
{5,0,0,0,9,0,0,0,0},
{0,8,0,3,0,0,5,0,0},
{0,0,0,8,0,0,0,0,0},
{0,0,9,0,0,0,0,7,3},
{0,5,0,9,0,0,0,0,2}};

int ma2[][]={
{0,0,0,0,8,4,0,0,0},//8
{0,0,0,2,0,3,0,8,0},
{8,3,0,9,0,0,0,5,0},
{0,5,3,0,9,0,7,0,0},
{0,0,0,6,3,7,0,4,5},//7
{0,7,0,5,0,0,0,0,0},
{0,0,6,8,0,0,0,0,0},
{3,0,0,0,2,9,0,0,0},
{2,0,9,3,0,0,0,0,1}};//3

The most difficult Sudoku in the world
Int[][] Sudoku = {
{8, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 3, 6, 0, 0, 0, 0, 0},
{0, 7, 0, 0, 9, 0, 2, 0, 0},
{0, 5, 0, 0, 0, 7, 0, 0, 0},
{0, 0, 0, 0, 4, 5, 7, 0, 0},
{0, 0, 0, 1, 0, 6, 0, 3, 0},
{0, 0, 1, 0, 0, 0, 0, 6, 8},
{0, 0, 8, 5, 0, 0, 0, 1, 0},
{0, 9, 0, 0, 0, 0, 4, 0, 0}};

Matrix M = new matrix (sudoku);
M.backtrack (0, 0);
}

}