https://leetcode.com/problems/valid-sudoku/

    1. class Solution {
    2. public:
    3.     bool isValidSudoku(vector<vector<char>>& board) {
    5.         int sub_r, sub_c;
    7.         for(int r = 0; r < 9; r++){
    8.             for(int c = 0; c < 9; c++){
    10.                 if(isdigit(board[r][c])){
    11.                     for(int r_o = 0; r_o < 9; r_o++){
    12.                         if(board[r_o][c] == board[r][c] && r_o != r){
    13.                             return false;
    14.                         }
    15.                     }
    17.                     for(int c_o = 0; c_o < 9; c_o++){
    18.                         if(board[r][c_o] == board[r][c] && c_o != c){
    19.                             return false;
    20.                         }
    21.                     }
    23.                     if(r <= 2){
    24.                         sub_r = 0;
    25.                     } else if(r >= 3 && r <= 5){
    26.                         sub_r = 1;
    27.                     } else {
    28.                         sub_r = 2;
    29.                     }
    31.                     if(c <= 2){
    32.                         sub_c = 0;
    33.                     } else if(c >= 3 && c <= 5){
    34.                         sub_c = 1;
    35.                     } else {
    36.                         sub_c = 2;
    37.                     }
    39.                     for(int r_s = 3*sub_r; r_s < 3*(sub_r + 1); r_s++){
    40.                         for(int c_s = 3*sub_c; c_s < 3*(sub_c + 1); c_s++){
    41.                             if(board[r_s][c_s] == board[r][c] && !(r_s == r && c_s == c)){
    42.                                 return false;
    43.                             }
    44.                         }
    45.                     }
    46.                 }
    47.             }
    48.         }
    50.         return true;
    51.     }
    53. };
    func isValidSudoku(board [][]byte) bool {
    for y:=0; y<9; y++ {
        for x:=0; x<9; x++ {
            if !allValid(board, y, x){
                return false
            }
        }
    }

    return true
}

func verticalValid(board [][]byte, y int, x int) bool {
    val := board[y][x]

    for i:=0; i<9; i++ {
        if board[i][x] == val && i != y {
            return false
        }
    }
    return true
}

func horizontalValid(board [][]byte, y int, x int) bool {
    val := board[y][x]

    for j:=0; j<9; j++ {
        if board[y][j] == val && j != x {
            return false
        }
    }
    return true
}

func cubeValid(board [][]byte, y int, x int) bool {
    val := board[y][x]
    i_o := int(y / 3) * 3 
    j_o := int(x / 3) * 3

    for i:=i_o; i < i_o + 3; i++ {
        for j:=j_o; j < j_o + 3; j++ {
            if board[i][j] == val && !(j == x && i == y) {
                return false
            }
        }
    }
    return true
}

func allValid(board [][]byte, y int, x int) bool {
    if board[y][x] == '.' {
        return true
    }
    if !verticalValid(board, y, x){
        return false
    }
    if !horizontalValid(board, y, x){
        return false
    }
    if !cubeValid(board, y, x){
        return false
    }
    return true
}