Valid Sudoku

class Solution {public:    bool isValidSudoku(vector<vector<char> > &board) {if( board.size()!=9 && board[0].size()!=9) return false;        char num[10]={0};//check rowsfor(size_t i=0;i<board.size();i++){memset(num,0,sizeof(char)*10);for(size_t j=0;j<board[i].size();j++){if(board[i][j]!='.'){const int index=board[i][j]-'0';if(index<1 || index>9 || num[index]>=1){return false;}else{num[index]=1;}}}}//check columnsfor(size_t j=0;j<board[0].size();j++){memset(num,0,sizeof(char)*10);for(size_t i=0;i<board.size();i++){if(board[i][j]!='.'){const int index=board[i][j]-'0';if(index<1 || index>9 || num[index]>=1){return false;}else{num[index]=1;}}}}//check boxsconst int a[9]={0,3,6,27,30,33,54,57,60};for(int i=0;i < 9;i++){memset(num,0,sizeof(char)*10);for(int p=a[i],times=0;times<9;times++){if(times%3 == 0){p=a[i]+times*3;}else{p++;}if(board[p/9][p%9]!='.'){const int index=board[p/9][p%9]-'0';if(index<1 || index>9 || num[index]>=1){return false;}else{num[index]=1;}}}}return true;    }};