edit the following code to read in the sudoku puzzle from a text file. #include #include  int sudoku[9][9]= { 0,0,0,0,0,4,0,0,0, 0,6,8,0,0,0,5,0,0, 0,2,0,0,0,0,0,7,6, 6,0,0,0,0,0,8,9,0, 0,0,5,2,6,0,0,0,0, 0,0,0,9,0,0,1,0,0, 0,0,0,0,0,7,0,5,0, 0,4,0,0,0,0,0,0,1, 0,0,0,0,5,1,4,0,0 }; int a[9][9]= { 0,0,0,0,0,4,0,0,0, 0,6,8,0,0,0,5,0,0, 0,2,0,0,0,0,0,7,6, 6,0,0,0,0,0,8,9,0, 0,0,5,2,6,0,0,0,0, 0,0,0,9,0,0,1,0,0, 0,0,0,0,0,7,0,5,0, 0,4,0,0,0,0,0,0,1, 0,0,0,0,5,1,4,0,0 }; //PRINT SUDOKU void printSudoku() { int i,j; FILE *fp; FILE *fw; fp = fopen("in.txt", "r"); fw= fopen("out.txt", "w"); if(fp == NULL) { perror("Error while opening the file"); exit(EXIT_FAILURE); } char ch; while((ch = fgetc(fp))!=EOF){ if(j==9){ i++; j=0; } } for(i = 0; i < 9; i++) { if(i==3 || i==6) fprintf(fw, " "); for(j = 0; j < 9; j++) { fprintf(fw, "%d",sudoku[i][j]); fprintf(fw, " "); if(j>7) fprintf(fw, " "); if(j==2 || j==5) fprintf(fw, " "); } } fprintf(fw," "); fclose(fp); } //CHECK ROW int checkRow(int num, int i) { int j,x=1; for(j = 0; j < 9; j++) if(sudoku[i][j] == num) return 0; return x; } //CHECK COLUMN int checkCol(int num, int j) { int i,x=1; for(i = 0; i < 9; i++) if(sudoku[i][j]==num) return 0; return x; } //CHECK SQUARE int checkSquare(int num, int xj, int yi) { int x=1; int i,j; for(i = yi; i < yi+3; i++) for(j = xj; j < xj+3; j++) if(sudoku[i][j]==num) return 0; return x; } //MAIN PROGRAM main() { int i,j,num,row,col; int pi,pj,xj,yi,square; printSudoku(); for(i = 0; i < 9; i++) for(j = 0; j < 9; j++) { if(sudoku[i][j]==0) { num=1; do { if(num>9) { pi=i; if(j == 0) { if(i!=0) { pj=8; pi=i-1; } } else { pj=j-1; } for(i = pi; i >= 0; i--) for(j = pj; j >= 0; j--) { pj=8; if(a[i][j]==0 && sudoku[i][j]==9) { sudoku[i][j]=0; } else if(a[i][j]==0 && sudoku[i][j]<9) { num=sudoku[i][j]+1; sudoku[i][j]=0; goto check; } } } check:row=checkRow(num,i); col=checkCol(num,j); if(j<3) xj=0; if(j>2 && j<6) xj=3; if(j>5) xj=6; if(i<3) yi=0; if(i>2 && i<6) yi=3; if(i>5) yi=6; square=checkSquare(num,xj,yi); if(row==1 && col==1 && square==1) sudoku[i][j]=num; else num++; } while(row==0 || col==0 || square==0); } } printf(" "); printSudoku(); }