Valid Sudoku

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.

public class Solution {
    public boolean isValidSudoku(char[][] board) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(board == null || board.length != 9 || board[0].length != 9) return false;
        int[] checkr = new int[9];
        int[] checkc = new int[9];
        for(int i = 0; i < 9; i ++){
            for(int j = 0; j < 9; j ++){
                if(board[i][j] - '0' > 0 && board[i][j] - '0' < 10){
                    checkr[board[i][j] - '0' - 1] ++;
                }
                if(board[j][i] - '0' > 0 && board[j][i] - '0' < 10){
                    checkc[board[j][i] - '0' - 1] ++;
                }
            }
            for(int ii = 0; ii < 9; ii ++){
                if(checkr[ii] > 1 || checkc[ii] > 1){
                    return false;
                }
            }
            checkr = new int[9];
            checkc = new int[9];
        }
        for(int i = 0; i < 9; i ++){
            for(int j = 0; j < 3; j ++){
                if(board[i][j] != '.')
                    checkc[board[i][j] - '0' - 1] ++;
            }
            if((i + 1) % 3 == 0){
                for(int ii = 0; ii < 9; ii ++){
                    if(checkr[ii] > 1 || checkc[ii] > 1){
                        return false;
                    }
                }
                checkc = new int[9];
                }
            }
        
        checkc = new int[9];
        for(int i = 0; i < 9; i ++){
            for(int j = 3; j < 6; j ++){
                if(board[i][j] != '.')
                    checkc[board[i][j] - '0' - 1] ++;
            }
            if((i + 1) % 3 == 0){
                for(int ii = 0; ii < 9; ii ++){
                    if(checkr[ii] > 1 || checkc[ii] > 1){
                        return false;
                    }
                }
                checkc = new int[9];
                }
            }
        
        checkc = new int[9];
        for(int i = 0; i < 9; i ++){
            for(int j = 6; j < 9; j ++){
                if(board[i][j] != '.')
                    checkc[board[i][j] - '0' - 1] ++;
            }
            if((i + 1) % 3 == 0){
                for(int ii = 0; ii < 9; ii ++){
                    if(checkr[ii] > 1 || checkc[ii] > 1){
                        return false;
                    }
                }
                checkc = new int[9];
                }
            }
        
        return true;
    }
}

 第二遍：

public class Solution {
    public boolean isValidSudoku(char[][] board) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(board == null || board.length != 9 || board[0].length != 9) return false;
        boolean[] checkr = new boolean[9];
        boolean[] checkc = new boolean[9];
        for(int i = 0; i < 9; i ++){
            checkr = new boolean[9];
            checkc = new boolean[9];
            for(int j = 0; j < 9; j ++){
                if ( board[i][j] != '.'){
                    if(checkr[board[i][j] - '1']) return false;
                    checkr[board[i][j] - '1'] = true;
                }
                if ( board[j][i] != '.'){
                    if(checkc[board[j][i] - '1']) return false;
                    checkc[board[j][i] - '1'] = true;
                }
            }
        }
        for(int a = 0; a < 3; a ++){
            for(int b = 0; b < 3; b ++){
                checkr = new boolean[9];
                for(int i = a * 3; i < (a + 1) * 3; i ++){
                    for(int j = b * 3; j < (b + 1) *3; j ++){
                        if ( board[i][j]!='.' ){
                            if(checkr[board[i][j] - '1']) return false;
                            checkr[board[i][j] - '1'] = true;
                        }
                    }
                }
            }
        }
        return true;
    }
}

 第三遍：

public class Solution {
    public boolean isValidSudoku(char[][] board) {
        if(board == null || board.length != 9 || board[0].length != 9) return false;
        boolean[] value = new boolean[9];
        for(int i = 0; i < 9; i ++){
            value = new boolean[9];
            for(int j = 0; j < 9; j ++){
                if(board[i][j] != '.' && value[board[i][j] - '1']) return false;
                else if(board[i][j] != '.' && !value[board[i][j] - '1']) value[board[i][j] - '1'] = true;
            }
            value = new boolean[9];
            for(int j = 0; j < 9; j ++){
                if(board[j][i] != '.' && value[board[j][i] - '1']) return false;
                else if(board[j][i] != '.' && !value[board[j][i] - '1']) value[board[j][i] - '1'] = true;
            }
        }
        for(int k = 0; k < 3; k ++){
            for(int h = 0; h < 3; h ++){
                value = new boolean[9];
                for(int i = 3*k; i < 3*k + 3; i ++){
                    for(int j = 3*h; j < 3*h + 3; j ++){
                        if(board[i][j] != '.' && value[board[i][j] - '1']) return false;
                        else if(board[i][j] != '.' && !value[board[i][j] - '1']) value[board[i][j] - '1'] = true;
                    }
                }
            }
        }
        return true;
    }
}