[LeetCode]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.

Note:

A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

题解：验证矩阵的每一行是否有重复元素，每一列是否有重复元素，每一3X3的小矩形是否有重复元素，用visited数组来保存是已经存在的元素。

code：

public boolean isValidSudoku(char[][] board) {
		
		boolean[] visited = new boolean[9];
		//用来遍历每一行
		for(int i=0; i<9; i++){
			Arrays.fill(visited, false);
			for(int j=0; j<9; j++){
				if(!process(visited, board[i][j])){
					return false;
				}
			}
		}
		//用来遍历每一列
		for(int i=0; i<9; i++){
			Arrays.fill(visited, false);
			for(int j=0; j<9;j++){
				if(!process(visited,board[j][i])){
					return false;
				}
			}
		}
		//遍历小矩阵
		for(int i=0; i<9; i+=3){
			
			for(int j=0; j<9; j+=3){
				Arrays.fill(visited, false);
				for(int k=0; k<9; k++){
					if(!process(visited, board[i+k/3][j+k%3])){
						return false;
					}
				}
			}
		}
		return true;
	}
	//判断是否为.和元素是否已经访问
	public boolean process(boolean [] visited,char digit){
		
		if(digit=='.'){
			return true;
		}
		int num = digit - '0';
		if(num< 1 || num>9 || visited[num-1]){
			return false;
		}
		visited[num-1] = true;
		return true;
	}

参考： http://www.jiuzhang.com/solutions/valid-sudoku/