[LeetCode][Kotlin] 36. Valid Sudoku

36. Valid Sudoku

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

1. Each row must contain the digits 1-9 without repetition.
2. Each column must contain the digits 1-9 without repetition.
3. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.

Note:

• A Sudoku board (partially filled) could be valid but is not necessarily solvable.
• Only the filled cells need to be validated according to the mentioned rules.

9 x 9 스도쿠 보드가 유효한지 확인합니다. 다음 규칙에 따라 채워진 셀만 검증하면 됩니다. 
1. 각 행에는 반복 없이 숫자 1~9가 포함되어야 합니다. 
2. 각 열에는 반복 없이 숫자 1~9가 포함되어야 합니다. 
3. 그리드의 9개의 3 x 3 하위 상자 각각에는 반복 없이 숫자 1~9가 포함되어야 합니다. 

메모: 
- 스도쿠 보드(부분적으로 채워짐)는 유효할 수 있지만 반드시 풀 수 있는 것은 아닙니다. 
- 언급된 규칙에 따라 채워진 셀만 검증하면 됩니다.

 

Example 1:

Input: board = 

[["5","3",".",".","7",".",".",".","."]

,["6",".",".","1","9","5",".",".","."]

,[".","9","8",".",".",".",".","6","."]

,["8",".",".",".","6",".",".",".","3"]

,["4",".",".","8",".","3",".",".","1"]

,["7",".",".",".","2",".",".",".","6"]

,[".","6",".",".",".",".","2","8","."]

,[".",".",".","4","1","9",".",".","5"]

,[".",".",".",".","8",".",".","7","9"]]

Output: true

 

Example 2:

Input: board = 

[["8","3",".",".","7",".",".",".","."]

,["6",".",".","1","9","5",".",".","."]

,[".","9","8",".",".",".",".","6","."]

,["8",".",".",".","6",".",".",".","3"]

,["4",".",".","8",".","3",".",".","1"]

,["7",".",".",".","2",".",".",".","6"]

,[".","6",".",".",".",".","2","8","."]

,[".",".",".","4","1","9",".",".","5"]

,[".",".",".",".","8",".",".","7","9"]]

Output: false

Explanation: Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.

 

Constraints:

• board.length == 9
• board[i].length == 9
• board[i][j] is a digit 1-9 or '.'.

---

코드 1

class Solution {
    fun isValidSudoku(board: Array<CharArray>): Boolean {
        val rowMap = HashMap<Int, HashSet<Char>>()
        val colMap = HashMap<Int, HashSet<Char>>()
        val squareMap = HashMap<Pair<Int, Int>, HashSet<Char>>()

        for (i in board.indices) {
            for (j in board[i].indices) {
                val now = board[i][j]
                if (now != '.') {
                    // if (!rowMap.containsKey(i)) {
                    if (i !in rowMap) {
                        rowMap[i] = HashSet()
                    }
                    if (j !in colMap) {
                        colMap[j] = HashSet()
                    }
                    if (Pair(i / 3, j / 3) !in squareMap) {
                        squareMap[Pair(i / 3, j / 3)] = HashSet()
                    }

                    if (rowMap[i]!!.contains(now) ||
                        colMap[j]!!.contains(now) ||
                        squareMap[Pair(i / 3, j / 3)]!!.contains(now)
                    ) {
                        return false
                    }

                    rowMap[i]!!.add(now)
                    colMap[j]!!.add(now)
                    squareMap[Pair(i / 3, j / 3)]!!.add(now)
                }
            }
        }

        return true
    }
}

 

코드 2

class Solution {
    fun isValidSudoku(board: Array<CharArray>): Boolean {
        val rowSet = Array(9) { HashSet<Char>() }
        val colSet = Array(9) { HashSet<Char>() }
        val squareSet = Array(9) { HashSet<Char>() }

        for (i in board.indices) {
            for (j in board[i].indices) {
                val now = board[i][j]
                if (now != '.') {
                    val squareIndex = (i / 3) * 3 + (j / 3)

                    if (now in rowSet[i] || 
                        now in colSet[j] || 
                        now in squareSet[squareIndex]
                    ) {
                        return false
                    }

                    rowSet[i].add(now)
                    colSet[j].add(now)
                    squareSet[squareIndex].add(now)
                }
            }
        }

        return true
    }
}