题目

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.

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 '.'.

思路

方法1 (Java)

设置一个Set集合,遍历数独表二维数组,将当前遍历到的位置的元素以3个字符串形式记录下它所在的行,列和九宫格信息,并加入Set集合。若Set集合中存在某一元素的任意行/列/九宫格信息,则认为该表不符合规则。

设当前元素值为val,位置为(i, j),位于第i/3*3+j/3个九宫格(从0开始),则该元素的信息可以设置为:

行信息:"val in row i"

列信息:"val in col j"

九宫格信息:"val in box i/3*3+j/3"

class Solution {
public boolean isValidSudoku(char[][] board) {
HashSet<String> set = new HashSet<>();
for(int i = 0; i < 9; i++){
for(int j = 0; j < 9; j++){
if(board[i][j] == '.') continue;
String row = board[i][j] + " in row " + i;
String col = board[i][j] + " in col " + j;
String box = board[i][j] + " in box " + (i/3*3+j/3);
if(set.contains(row) || set.contains(col) || set.contains(box)) return false;
set.add(row);
set.add(col);
set.add(box);
}
}
return true;
}
}

方法2(Java)

0-8,对每一个i,设置3个boolean数组分别检测第i行、第i列和第i个九宫格,数组的index代表被检测的值。

对于每个i的值,j0-8意味着检测:

i行, 第j个数是否已位于行i中;

i列,第j个数是否已位于列i中;

i个九宫格中,该九宫格从左上角到右下角的第j数是否已位于该九宫格中。

 

设置3个数组,

boolean[] checkRow 检查位置(i, j)的值是否已存在第i行

boolean[] checkCol 检查位置(j, i)的值是否已存在第i列

boolean[] checkBox 检查位置(i/3*3+j/3, j%3*3+j%3)的值是否已存在第i个九宫格中

例如当i为4,j从0-8,对应行、列、九宫格的遍历过程

  0 1 2   3 4 5   6 7 8
0 o o o | o 1 o | o o o
1 o o o | o 2 o | o o o
2 o o o | o 3 o | o o o
------------------------
3 o o o | o 4 o | o o o
4 1 2 3 | 4 5 6 | 7 8 9
5 o o o | o 6 o | o o o
------------------------
6 o o o | o 7 o | o o o
7 o o o | o 8 o | o o o
8 o o o | o 9 o | o o o 第4个九宫格中
1 2 3
4 5 6
7 8 9
class Solution {
public boolean isValidSudoku(char[][] board) {
for(int i = 0; i < 9; i++){
boolean[] checkRow = new boolean[9];
boolean[] checkCol = new boolean[9];
boolean[] checkBox = new boolean[9];
for(int j = 0; j < 9; j++){
if(board[i][j] == '.') {}
else if(checkRow[board[i][j]-'1']) return false;
else checkRow[board[i][j]-'1'] = true; if(board[j][i] == '.'){}
else if(checkCol[board[j][i]-'1']) return false;
else checkCol[board[j][i]-'1'] = true; int m = i/3*3+j/3, n = i%3*3+j%3;
if(board[m][n] == '.'){}
else if(checkBox[board[m][n]-'1']) return false;
else checkBox[board[m][n]-'1'] = true;
}
}
return true;
}
}

LeetCode 36. Valid Sudoku (Medium)的更多相关文章

  1. LeetCode:36. Valid Sudoku,数独是否有效

    LeetCode:36. Valid Sudoku,数独是否有效 : 题目: LeetCode:36. Valid Sudoku 描述: Determine if a Sudoku is valid, ...

  2. 蜗牛慢慢爬 LeetCode 36.Valid Sudoku [Difficulty: Medium]

    题目 Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board could ...

  3. LeetCode 36 Valid Sudoku

    Problem: Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board ...

  4. Java [leetcode 36]Valid Sudoku

    题目描述: Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku board cou ...

  5. leetCode 36.Valid Sudoku(有效的数独) 解题思路和方法

    Valid Sudoku Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules. The Sudoku bo ...

  6. [LeetCode] 36. Valid Sudoku 验证数独

    Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to th ...

  7. [leetcode]36. Valid Sudoku验证数独

    Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to th ...

  8. LeetCode 36. Valid Sudoku (C++)

    题目: Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according t ...

  9. LeetCode 36 Valid Sudoku(合法的数独)

    题目链接: https://leetcode.com/problems/valid-sudoku/?tab=Description   给出一个二维数组,数组大小为数独的大小,即9*9  其中,未填入 ...

随机推荐

  1. ABP Framework 5.0 RC.1 新特性和变更说明

    .Net 6.0 发布之后,ABP Framework 也在第一时间进行了升级,并在一个多星期后(2021-11-16)发布了 5.0 RC.1 ,新功能和重要变更基本已经确定. 5.0版本新特性 新 ...

  2. 行星万象表白墙微信小程序、社交微信小程序,后台完整,支持多区域运营,扫码体验。

    简介 中国目前大概有5000个表白墙,累计用户近3000万,是一个庞大的群体,但现在大都以微信朋友圈为基础进行信息中转,但是这种模式经营者和用户都不友好,尤其是经营者无法变现,用户无法公开评论,这些种 ...

  3. Spring Cloud Gateway自定义过滤器实战(观测断路器状态变化)

    欢迎访问我的GitHub https://github.com/zq2599/blog_demos 内容:所有原创文章分类汇总及配套源码,涉及Java.Docker.Kubernetes.DevOPS ...

  4. [noi32]sort

    先解释一下checker.cpp,它的判定标准是2e7,即答案超过2e7就认为代价过大了. 首先,很容易想到的办法是直接对其快排,从外到内交换区间即可,然而这样会被邪恶的出题人给卡掉(当然其实随便一组 ...

  5. [atARC101F]Robots and Exits

    每一个点一定匹配其左边/右边的第一个出口(在最左/右边的出口左/右边的点直接删除即可),否则记到左右出口的距离分别为$x_{i}$和$y_{i}$ 令$p_{i}$表示$i$匹配的出口(左0右1),结 ...

  6. [nowcoder5668J]Operating on the Tree

    考虑令$a_{i}$为i的位置,$p_{i}=0/1$表示第i个点的贡献,那么$p_{x}=0$当且仅当存在与其相邻的点$y$满足$a_{y}<a_{x}$且$p_{y}=1$ 树形dp,定义状 ...

  7. javascript-初级-day02-this关键字

    day01-获取元素的第二种方法 <!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-T ...

  8. CF708E Student's Camp

    麻麻我会做*3100的计数了,我出息了 考虑朴素DP我们怎么做呢. 设\(f_{i,l,r}\)为第\(i\)层选择\(l,r\)的依旧不倒的概率. \(q(l,r)\)表示经历了\(k\)天后,存活 ...

  9. CF1578I Interactive Rays:ICPC WF Moscow Invitational Contest I 题解

    题意简述:在平面上有一个坐标 \((x_c,y_c)\) 和半径 \(r\) 都是整数的圆 \((1\leq r_c\leq \sqrt{x_c^2+y_c^2}-1)\),你可以询问不超过 \(60 ...

  10. R包customLayout比例拼图

    一个简单的需求: 拼接两个图,一行两列,但不要一样大,让主图占的比例大些(如2/3),另一个图小一些(如1/3) 如上,我想突出曼哈顿图. R相关的拼图函数及包: 基础函数如par(mar =c(3, ...