The document contains code for solving Sudoku puzzles. It initializes empty 9x9 matrices to hold the input puzzle and solution. It then validates the input, checks for duplicate values, and uses backtracking to solve the puzzle, outputting each solution found. The code continues searching for solutions until it has either found 50 solutions or exhausted all possibilities.

1. /* SU DOKU */
#include <iostream.h>
voidmain()
{
intk[9][9],K[9][9];
inti,j,i1,j1,i2,j2;
interror,temp;
intcount=0;
for(i=0;i<9;i++)
for(j=0;j<9;j++)
K[i][j]=0;
for(i=0;i<9;i++)
for(j=0;j<9;j++)
{
cin>>K[i][j];
k[i][j]=K[i][j];
}
cout<<"O.K.?(Enter0 if OK,1 to update):";
cin>>error;
if(error==0)
goto matrixvalidation;

2. matrixupdation:
while(1)
{
cout<<"Enter Row,Col,Revisednumber:(0toexit) ";
cin>>i;
if(i==0)break;
cin>>j>>temp;
if(i>0&&j>0&&temp>=0&&i<10&&j<10&&temp<10)
{
K[i-1][j-1]=temp;
k[i-1][j-1]=temp;
}
else
cout<<"Enter row/column1to 9 & number0 to9 only.
";
}
matrixvalidation:
cout<<"
Inputmatrix:
";
for(i=0;i<9;i++)
{
for(j=0;j<9;j++)
cout<<k[i][j]<<"";

3. cout<<"
";
}
for(i=0;i<9;i++)
for(j=0;j<9;j++)
if(k[i][j]<0||k[i][j]>9)
{
cout<<"
"<<i+1<<" "<<j+1<<" "<<k[i][j];
cout<<"
Inputmatrix error.";
cout<<"
Numbersshouldbe 1to 9 only.
";
goto matrixupdation;
}
for(i=0;i<9;i++)
for(j=0;j<9;j++)
{
if(k[i][j]==0)continue;
error=0;
for(i1=0;i1<9;i1++)

4. if(i!=i1&&k[i][j]==k[i1][j])
{
error=1;
i2=i1;
j2=j;
}
for(j1=0;j1<9;j1++)
if(j!=j1&&k[i][j]==k[i][j1])
{
error=1;
i2=i;
j2=j1;
}
for(i1=0;i1<9;i1++)
for(j1=0;j1<9;j1++)
if((i!=i1||j!=j1)&&i/3==i1/3&&j/3==j1/3&&k[i][j]==k[i1][j1])
{
error=1;
i2=i1;
j2=j1;
}
if(error)
{
cout<<"
"<<i+1<<" "<<j+1<<" "<<k[i][j];

5. cout<<"
"<<i2+1<<" "<<j2+1<<" "<<k[i2][j2];
cout<<"
Inputmatrix error.";
cout<<"
A numberhasbeenrepeatedinthe same row,col or
block.
";
goto matrixupdation;
}
}
/* Logic starts: */
for(i=0;i<9;i++)
for(j=0;j<9;j++)
{
if(K[i][j]>0) gotochksol;
for(k[i][j]++;k[i][j]<=9;k[i][j]++)
{
error=0;
for(i1=0;i1<9;i1++)
if(i!=i1&&k[i][j]==k[i1][j])error=1;
for(j1=0;j1<9;j1++)
if(j!=j1&&k[i][j]==k[i][j1])error=1;

6. for(i1=0;i1<9;i1++)
for(j1=0;j1<9;j1++)
if((i!=i1||j!=j1)&&i/3==i1/3&&j/3==j1/3&&k[i][j]==k[i1][j1])
error=1;
if(error==0)break;
}
if(k[i][j]>9)
{
k[i][j]=0;
do
{
if(i==0&&j==0)gotonomoresol;
if(j>0)j--;else{j=8;i--;}
}while(K[i][j]>0);
j--;
}
chksol: if(i==8&&j==8)
{
cout<<"
Solution:"<<++count<<"
";
for(i1=0;i1<9;i1++)
{
for(j1=0;j1<9;j1++)
cout<<k[i1][j1]<<"";

7. cout<<"
";
}
if(count==50)
{
cout<<"
Too manysolutions.
Notcheckingformore
solutions.
";
return;
}
while(K[i][j]>0)
{
if(i==0&&j==0)gotonomoresol;
if(j>0)j--;else{j=8;i--;}
}
k[i][j]=0;
do
{
if(i==0&&j==0)gotonomoresol;
if(j>0)j--;else{j=8;i--;}
}while(K[i][j]>0);

8. j--;
}
}
nomoresol:
if(count>0)
cout<<"
No more solutions.
";
else
cout<<"No solution.
";
}
/* SU DOKU */
#include <iostream.h>
voidmain()
{
intk[9][9],K[9][9];
inti,j,i1,j1,i2,j2;
interror,temp;
intcount=0;

9. for(i=0;i<9;i++)
for(j=0;j<9;j++)
K[i][j]=0;
for(i=0;i<9;i++)
for(j=0;j<9;j++)
{
cin>>K[i][j];
k[i][j]=K[i][j];
}
cout<<"O.K.?(Enter0 if OK,1 to update):";
cin>>error;
if(error==0)
goto matrixvalidation;
matrixupdation:
while(1)
{
cout<<"Enter Row,Col,Revisednumber:(0toexit) ";
cin>>i;
if(i==0)break;
cin>>j>>temp;
if(i>0&&j>0&&temp>=0&&i<10&&j<10&&temp<10)
{

10. K[i-1][j-1]=temp;
k[i-1][j-1]=temp;
}
else
cout<<"Enter row/column1to 9 & number0 to9 only.
";
}
matrixvalidation:
cout<<"
Inputmatrix:
";
for(i=0;i<9;i++)
{
for(j=0;j<9;j++)
cout<<k[i][j]<<"";
cout<<"
";
}
for(i=0;i<9;i++)
for(j=0;j<9;j++)
if(k[i][j]<0||k[i][j]>9)
{
cout<<"

11. "<<i+1<<" "<<j+1<<" "<<k[i][j];
cout<<"
Inputmatrix error.";
cout<<"
Numbersshouldbe 1to 9 only.
";
goto matrixupdation;
}
for(i=0;i<9;i++)
for(j=0;j<9;j++)
{
if(k[i][j]==0)continue;
error=0;
for(i1=0;i1<9;i1++)
if(i!=i1&&k[i][j]==k[i1][j])
{
error=1;
i2=i1;
j2=j;
}
for(j1=0;j1<9;j1++)
if(j!=j1&&k[i][j]==k[i][j1])
{

12. error=1;
i2=i;
j2=j1;
}
for(i1=0;i1<9;i1++)
for(j1=0;j1<9;j1++)
if((i!=i1||j!=j1)&&i/3==i1/3&&j/3==j1/3&&k[i][j]==k[i1][j1])
{
error=1;
i2=i1;
j2=j1;
}
if(error)
{
cout<<"
"<<i+1<<" "<<j+1<<" "<<k[i][j];
cout<<"
"<<i2+1<<" "<<j2+1<<" "<<k[i2][j2];
cout<<"
Inputmatrix error.";
cout<<"
A numberhasbeenrepeatedinthe same row,col or
block.
";

13. goto matrixupdation;
}
}
/* Logic starts: */
for(i=0;i<9;i++)
for(j=0;j<9;j++)
{
if(K[i][j]>0) gotochksol;
for(k[i][j]++;k[i][j]<=9;k[i][j]++)
{
error=0;
for(i1=0;i1<9;i1++)
if(i!=i1&&k[i][j]==k[i1][j])error=1;
for(j1=0;j1<9;j1++)
if(j!=j1&&k[i][j]==k[i][j1])error=1;
for(i1=0;i1<9;i1++)
for(j1=0;j1<9;j1++)
if((i!=i1||j!=j1)&&i/3==i1/3&&j/3==j1/3&&k[i][j]==k[i1][j1])
error=1;
if(error==0)break;
}
if(k[i][j]>9)
{
k[i][j]=0;

14. do
{
if(i==0&&j==0)gotonomoresol;
if(j>0)j--;else{j=8;i--;}
}while(K[i][j]>0);
j--;
}
chksol: if(i==8&&j==8)
{
cout<<"
Solution:"<<++count<<"
";
for(i1=0;i1<9;i1++)
{
for(j1=0;j1<9;j1++)
cout<<k[i1][j1]<<"";
cout<<"
";
}
if(count==50)
{
cout<<"
Too manysolutions.
Notcheckingformore
solutions.

15. ";
return;
}
while(K[i][j]>0)
{
if(i==0&&j==0)gotonomoresol;
if(j>0)j--;else{j=8;i--;}
}
k[i][j]=0;
do
{
if(i==0&&j==0)gotonomoresol;
if(j>0)j--;else{j=8;i--;}
}while(K[i][j]>0);
j--;
}
}
nomoresol:
if(count>0)
cout<<"
No more solutions.
";

16. else
cout<<"No solution.
";
}