Leetcode -- Valid Sudoku

题目：

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.

分析：

规则很简单，不要有重复的数字就好。遍历一遍，是必需的，也只能遍历一遍。复杂度高了，肯定不过不了。

代码：

class Solution {
public:
bool isValidSudoku(vector<vector<char>>& board) {
vector< vector<int> > arr(10, vector<int>(10, 0));
vector<vector<int>> smallArr(10, vector<int>(10, 0));
vector<vector<int>> col(10, vector<int>(10, 0));
int num;
for(int i = 0; i<= 6; i = i + 3)
{
for(int j = 0; j<= 6; j = j + 3)
{
for(int a = 0; a< 3; a++)
{
for(int b =0; b<3; b++)
{
if(board[i+a][j+b] != '.')
{
num = board[i+a][j+b] - '0';
arr[i +a][num] ++;
smallArr[i + j/3][num] ++;
col[j + b][num] ++;
if(arr[i+a][num] > 1 || smallArr[i + j/3][num]> 1 || col[j + b][num] > 1)
{
return false;
}

}
}
}
}
}
return true;
}
};

注意：

下标什么时候结束的问题。第一次刷的时候，下标的边界弄错了，调试了好久，sad！

一旦涉及到循环，下标的边界一定要好好检查一下。