#4 Daily Problems -Sudoku2

Hi Friends, I have solved the array related problem in fourth day.

Problem:

Sudoku is a number-placement puzzle. The objective is to fill a 9 × 9 grid with numbers in such a way that each column, each row, and each of the nine 3 × 3 sub-grids that compose the grid all contain all of the numbers from 1 to 9 one time.

Implement an algorithm that will check whether the given grid of numbers represents a valid Sudoku puzzle according to the layout rules described above. Note that the puzzle represented by grid does not have to be solvable.

Example

• For
• grid = [['.', '.', '.', '1', '4', '.', '.', '2', '.'], ['.', '.', '6', '.', '.', '.', '.', '.', '.'], ['.', '.', '.', '.', '.', '.', '.', '.', '.'], ['.', '.', '1', '.', '.', '.', '.', '.', '.'], ['.', '6', '7', '.', '.', '.', '.', '.', '9'], ['.', '.', '.', '.', '.', '.', '8', '1', '.'], ['.', '3', '.', '.', '.', '.', '.', '.', '6'], ['.', '.', '.', '.', '.', '7', '.', '.', '.'], ['.', '.', '.', '5', '.', '.', '.', '7', '.']
• the output should be
  sudoku2(grid) = true;
• For
• grid = [['.', '.', '.', '.', '2', '.', '.', '9', '.'], ['.', '.', '.', '.', '6', '.', '.', '.', '.'], ['7', '1', '.', '.', '7', '5', '.', '.', '.'], ['.', '7', '.', '.', '.', '.', '.', '.', '.'], ['.', '.', '.', '.', '8', '3', '.', '.', '.'], ['.', '.', '8', '.', '.', '7', '.', '6', '.'], ['.', '.', '.', '.', '.', '2', '.', '.', '.'], ['.', '1', '.', '2', '.', '.', '.', '.', '.'], ['.', '2', '.', '.', '3', '.', '.', '.', '.']]
• the output should be
  sudoku2(grid) = false.
• The given grid is not correct because there are two 1s in the second column. Each column, each row, and each 3 × 3 subgrid can only contain the numbers 1 through 9 one time.

Input/Output

• [execution time limit] 3 seconds (java)
• [input] array.array.char grid
• A 9 × 9 array of characters, in which each character is either a digit from '1' to '9' or a period '.'.
• [output] boolean
• Return true if grid represents a valid Sudoku puzzle, otherwise return false.

My solution:

boolean sudoku2(char[][] grid) {
int rowLength = grid.length;
int colLenght = grid.length;
System.out.println("rowLenght : "+rowLength+ "   colLenght: "+colLenght);
for (int r = 0; r < rowLength; r++) {
HashSet<Character> hashCol = new HashSet<Character>();
for (int c = 0; c < colLenght; c++) {
HashSet<Character> hashRow = new HashSet<Character>();
for (int row=0;row<rowLength;row++){
if (grid[row][c] != '.') {
//                    System.out.println("value exist: "+hashRowCol.contains(grid[r][c]));
if (hashRow.contains(grid[row][c]))
return false;
else
hashRow.add(grid[row][c]);
}
}
if (grid[r][c] != '.') {
//                    System.out.println("value exist: "+hashRowCol.contains(grid[r][c]));
if (hashCol.contains(grid[r][c]))
return false;
else
hashCol.add(grid[r][c]);
}
if ((r==0 || r==3 | r==6 )&& (c==0 || c==3 || c==6)) {
HashSet<Character> hashSub = new HashSet<Character>();
for (int sr = r; sr < r + 3; sr++) {
 for (int sc = c; sc < c + 3; sc++) {
if (grid[sr][sc] != '.') {
if (hashSub.contains(grid[sr][sc]))
return false;
else
hashSub.add(grid[sr][sc]);
}
}
}
}
}
}
return true;
}

I guess I have used some loops to complete this task. I have to work on that thing try to optimize this solution. Please give me any suggestion to improve this solution. thanks guys