[Leetcode 24] 35 Valid Sudoku

Problem:

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

A partially filled sudoku which is valid.

 

Analysis:

Simulation problem, the nice part here is use a same function for three different kinds of test as showed in code.

 

Code:

public class Solution {
    public boolean isValidSudoku(char[][] board) {
        // Start typing your Java solution below
        // DO NOT write main() function
        for (int i=0; i<9; ++i) {//judge row
            if (!judge(board, i, 0, 1, 9))
                return false;
        }
        
        for (int j=0; j<9; ++j) {//judge column
            if (!judge(board, 0, j, 9, 1))
                return false;
        }
        
        for (int i=0; i<3; ++i) {//judge block
            for (int j=0; j<3; ++j) {
                if (!judge(board, i*3, j*3, 3, 3))
                    return false;
            }
        }
        
        return true;
    }
    
    private boolean judge(char[][] board, int r, int c, int rl, int cl) {
        int[] hashT = {0,0,0,0,0,0,0,0,0};
        
        for (int i=r; i<r+rl; ++i) {
            for (int j=c; j<c+cl; ++j) {
                if (board[i][j] != '.') {
                    int idx = board[i][j]-'0'-1;
                    
                    if (hashT[idx] != 0) {
                        return false;
                    } else {
                        hashT[idx] ++;
                    }
                }
            }
        }
        
        return true;
    }
}

 

Attention:

Sometimes it may have Time Limit Exceeded error....