Leetcode 36 Effective Sudoku C++

topic

Please click

train of thought

• Use subscripts to store the number of occurrences of the corresponding element
• First two layers of for loop to judge whether each line meets the requirements
• Then two layers of for loop to judge whether each column meets the requirements
• Write a function to judge whether every three rows and three columns meet the requirements, and pass in parameters to change the end position of revelation

the code

bool isBoard(vector<vector<char>>& board, int b1, int b2, int e1, int e2){
    
    
    vector<int> numbers(10);
    for(int i=b1;i<e1;i++){
    
    
        for(int j=b2;j<e2;j++){
    
    
            if(board[i][j]=='.') continue;
            int n=board[i][j]-'0';
            numbers[n]++;
            if(numbers[n]>1) return false;
        }
    }
    return true;
}
bool isValidSudoku(vector<vector<char>>& board) {
    
    
    //先判断行
    for(int i=0;i<9;i++){
    
    
        vector<int> numbers(10);
        for(int j=0;j<9;j++){
    
    
            if(board[i][j]=='.') continue;
            int n=board[i][j]-'0';
            numbers[n]++;
            if(numbers[n]>1) return false;
        }
    }
    //判断列
    for(int j=0;j<9;j++){
    
    
        vector<int> numbers(10);
        for(int i=0;i<9;i++){
    
    
            if(board[i][j]=='.') continue;
            int n=board[i][j]-'0';
            numbers[n]++;
            if(numbers[n]>1) return false;
        }
    }
    //再判断3*3宫格
    bool ret1=isBoard(board, 0, 0, 3, 3);
    if(!ret1) return false;
    bool ret2=isBoard(board, 0, 3, 3, 6);
    if(!ret2) return false;
    bool ret3=isBoard(board, 0, 6, 3, 9);
    if(!ret3) return false;

    bool ret4=isBoard(board, 3, 0, 6, 3);
    if(!ret4) return false;
    bool ret5=isBoard(board, 3, 3, 6, 6);
    if(!ret5) return false;
    bool ret6=isBoard(board, 3, 6, 6, 9);
    if(!ret6) return false;

    bool ret7=isBoard(board, 6, 0, 9, 3);
    if(!ret7) return false;
    bool ret8=isBoard(board, 6, 3, 9, 6);
    if(!ret8) return false;
    bool ret9=isBoard(board, 6, 6, 9, 9);
    if(!ret9) return false;

    return true;
}