資工趴趴熊的小天地

class Solution {
private:
	bool backtracking(vector<vector<char>>& board) {
		for (int i = 0; i < board.size(); i++){ //跑直得 
			for (int j = 0; j < board[0].size(); j++){ //跑橫得 
				if (board[i][j] != '.') continue; //不是要跑的空格，跑下個迴圈 
				for (char k = '1'; k <= '9'; k++){ 
					if(isValid(i, j, k, board)){ // (i, j) 位置放k是否合適，若合適的話 
						board[i][j] = k; //就把數字填上去 
						if (backtracking(board)) return true; // 如果找到合适立刻返回
                    	board[i][j] = '.'; // 回溯，
					} 
					
				} 
				return false; // 9個數字都不行，那么就返回false
			} 
		}
		return true; // 跑完全不沒有返回false，就是找到答案了 
	}
	/*-----------------------------------------------------------------*/ 
	bool isValid(int row, int col, char val, vector<vector<char>>& board){
		//判斷橫的
		for (int i = 0; i < 9; i++) {
        	if (board[row][i] == val) {
            	return false;
        	}
    	} 
    	
    	//判斷直的
    	for (int j = 0; j < 9; j++) { 
	        if (board[j][col] == val) {
	            return false;
	        }
	    }
	    
	    //判斷小框框內9格是否重複 
	    int startRow = (row / 3) * 3;  
	    int startCol = (col / 3) * 3;
	    for (int i = startRow; i < startRow + 3; i++) { 
	        for (int j = startCol; j < startCol + 3; j++) {
	            if (board[i][j] == val ) {
	                return false;
	            }
	        }
	    }
	    return true;
	} 
	
	
public:
    void solveSudoku(vector<vector<char>>& board) {
    	backtracking(board);//引入函式 
        
        
    }
};