//题目：有效数独

class Solution {

public boolean isValidSudoku(char[][] board) {

if(board == null)

return false;

if(board.length !=9)

return false;

int[] map = new int[9];

for(int y=0; y<9; y++){

if(board[y] == null || board[y].length != 9)

return false;

for(int x=0; x<9; x++){

int key = board[y][x] - '1'; //key:数字

if(key >= 0 && key <= 8) { //1~9有效数字

int index = (1<<x) //Value:位置编码，最低9位存放列号

| (1<<(y+9)) //中间9位存放行号

| (1<<(x/3 + y/3*3 + 18)); // z为9宫格区域序号

int old = map[key];

if((old & index) == 0) //无重复，则按位或，加入位置集合

map[key] = old | index;

else //有重复

return false;

}

}

}

return true;

}

}