# C++ Programming Code Examples

## C++ > Mathematics Code Examples

### Ultimate sol. to world famous game Sudoku

``` Ultimate sol. to world famous game Sudoku /* SU DOKU */ #include <iostream.h> void main() { int k[9][9],K[9][9]; int i,j,i1,j1,i2,j2; int error,temp; int count=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.? (Enter 0 if OK, 1 to update): "; cin>>error; if(error==0) goto matrixvalidation; matrixupdation: while(1) { cout<<"Enter Row, Col, Revised number:(0 to exit) "; 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/column 1 to 9 & number 0 to 9 only. "; } matrixvalidation: cout<<" Input matrix: "; 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<<" "<<i+1<<" "<<j+1<<" "<<k[i][j]; cout<<" Input matrix error."; cout<<" Numbers should be 1 to 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]) { 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<<" Input matrix error."; cout<<" A number has been repeated in the 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) goto chksol; 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; do { if(i==0&&j==0)goto nomoresol; 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 many solutions. Not checking for more solutions. "; return; } while(K[i][j]>0) { if(i==0&&j==0)goto nomoresol; if(j>0)j--;else{j=8;i--;} } k[i][j]=0; do { if(i==0&&j==0)goto nomoresol; if(j>0)j--;else{j=8;i--;} }while(K[i][j]>0); j--; } } nomoresol: if(count>0) cout<<" No more solutions. "; else cout<<"No solution. "; } ```