面试经典150题——Day34

文章目录

一、题目

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:

Each row must contain the digits 1-9 without repetition.

Each column must contain the digits 1-9 without repetition.

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 '.'.

题目来源: leetcode

二、题解

我自己的笨方法

cpp 复制代码
class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        unordered_map<char,int> map;
        //遍历行
        for(int i = 0;i < 9;i++){
            //清除上行数据
            map.clear();
            for(int j = 0;j < 9;j++){
                char c = board[i][j];
                if(c != '.'){
                    if(map[c] == 0) map[c]++;
                    else if(map[c] == 1) return false;
                }
            }
        }
        //遍历列
        for(int j = 0;j < 9;j++){
            map.clear();
            for(int i = 0;i < 9;i++){
                char c = board[i][j];
                if(c != '.'){
                    if(map[c] == 0) map[c]++;
                    else if(map[c] == 1) return false;
                }
            }
        }
        //遍历3x3宫格
        for(int i = 0;i < 9;i += 3){
            for(int j = 0;j < 9;j += 3){
                map.clear();
                for(int k = i;k < i + 3;k++){
                    for(int m = j;m < j + 3;m++){
                        char c = board[k][m];
                        if(c != '.'){
                            if(map[c] == 0) map[c]++;
                            else if(map[c] == 1) return false;
                        }
                    }
                }
            }
        }
        return true;
    }
};

答案的好方法

cpp 复制代码
class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        int rows[9][9];
        int columns[9][9];
        int subboxes[3][3][9];
        
        memset(rows,0,sizeof(rows));
        memset(columns,0,sizeof(columns));
        memset(subboxes,0,sizeof(subboxes));
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                char c = board[i][j];
                if (c != '.') {
                    int index = c - '0' - 1;
                    rows[i][index]++;
                    columns[j][index]++;
                    subboxes[i / 3][j / 3][index]++;
                    if (rows[i][index] > 1 || columns[j][index] > 1 || subboxes[i / 3][j / 3][index] > 1) {
                        return false;
                    }
                }
            }
        }
        return true;
    }
};
相关推荐
hie9889410 分钟前
MATLAB锂离子电池伪二维(P2D)模型实现
人工智能·算法·matlab
Jay_51511 分钟前
C++多态与虚函数详解:从入门到精通
开发语言·c++
杰克尼20 分钟前
BM5 合并k个已排序的链表
数据结构·算法·链表
.30-06Springfield1 小时前
决策树(Decision tree)算法详解(ID3、C4.5、CART)
人工智能·python·算法·决策树·机器学习
我不是哆啦A梦1 小时前
破解风电运维“百模大战”困局,机械版ChatGPT诞生?
运维·人工智能·python·算法·chatgpt
xiaolang_8616_wjl1 小时前
c++文字游戏_闯关打怪
开发语言·数据结构·c++·算法·c++20
small_wh1te_coder1 小时前
硬件嵌入式学习路线大总结(一):C语言与linux。内功心法——从入门到精通,彻底打通你的任督二脉!
linux·c语言·汇编·嵌入式硬件·算法·c
FrostedLotus·霜莲1 小时前
C++主流编辑器特点比较
开发语言·c++·编辑器
hqxstudying2 小时前
Java创建型模式---单例模式
java·数据结构·设计模式·代码规范
挺菜的2 小时前
【算法刷题记录(简单题)002】字符串字符匹配(java代码实现)
java·开发语言·算法