【Leetcode】【中等】【36. 有效的数独】【JavaScript】

题目描述

36. 有效的数独

判断一个 9x9 的数独是否有效。只需要根据以下规则，验证已经填入的数字是否有效即可。

数字 1-9 在每一行只能出现一次。
数字 1-9 在每一列只能出现一次。
数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。

上图是一个部分填充的有效的数独。

数独部分空格内已填入了数字，空白格用 '.' 表示。

示例 1:

输入:

[
["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"]
]

输出: true

示例 2:

输入:

[
  ["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"]
]

输出: false
解释: 除了第一行的第一个数字从 5 改为 8 以外，空格内其他数字均与 示例1 相同。
但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。

说明:

一个有效的数独（部分已被填充）不一定是可解的。
只需要根据以上规则，验证已经填入的数字是否有效即可。
给定数独序列只包含数字 1-9 和字符 '.' 。
给定数独永远是 9x9 形式的。

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/valid-sudoku
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

解答：

解答：

个人思路：

　　1、检测每行是否有重复数字；

　　2、检测每列是否有重复数字；

　　3、检测每个3*3内是否有重复数字。

96ms

/**
 * @param {character[][]} board
 * @return {boolean}
 */
function isRepeat(arr) {
    let hash = {}
    for (let i = 0; i < arr.length; i++) {
        if (!isNaN(arr[i])) {
            if (hash[arr[i]]) {
                return false
            } else {
                hash[arr[i]] = 1
            }
        }

    }
    return true
}
var isValidSudoku = function (board) {
    let result
    let colArr = []
    let blockArr = []
    //每一行是否重复检测
    for (let i = 0; i < board.length; i++) {
        result = isRepeat(board[i])
        if (!result) {
            console.log('行重复')
            return false
        }
    }

    //每一列是否重复检测
    for (let i = 0; i < board.length; i++) {
        for (let j = 0; j < board[i].length; j++) {
            if (!colArr[j]) {
                colArr[j] = []
            }
            colArr[j].push(board[i][j])
        }
    }
    for (let i = 0; i < colArr.length; i++) {
        result = isRepeat(colArr[i])
        if (!result) {
            console.log('列重复')
            return false
        }
    }

    //3*3是否重复
    let block = 0
    for (let i = 0; i < board.length; i++) {
        let reset = block
        for (let j = 0; j < board[i].length; j++) {
            if (!blockArr[block]) {
                blockArr[block] = []
            }
            blockArr[block].push(board[i][j])
            if ((j + 1) % 3 === 0) {
                block++
            }
            if (j === 8) {
                block = reset
            }
        }
        if ((i + 1) % 3 === 0) {
            block += 3
        }
    }
    for (let i = 0; i < blockArr.length; i++) {
        result = isRepeat(blockArr[i])
        if (!result) {
            console.log('3*3重复')
            return false
        }
    }

    //以上三种检测都通过
    return true

};