题目描述
Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.
The Sudoku board could be partially filled, where empty cells are filled with the character'.'.
A partially filled sudoku which is valid.
代码:
方式1:
链接:https://www.nowcoder.com/questionTerminal/8240bcdab4eb496fb6c4ba634fc67921
来源:牛客网
import java.util.HashSet;
import java.util.Set;
/**
* 36. Valid Sudoku
*
* @author Jacob
*
*/
public class Demo1 {
/*
* 题意:让你判断这是否是一个正确的数独,
* 即确定每一行,每一列以及每一个九宫格是否有相同的数字
* HashSet的add方法,当添加成功(即set中不含有该元素)返回true
*/
public boolean isValidSudoku(char[][] board) {
// 每一个大循环确定一行,一列,一个九宫格
for (int i = 0; i < 9; i++) {
Set<Character> row = new HashSet<Character>();
Set<Character> col = new HashSet<Character>();
Set<Character> cube = new HashSet<Character>();
for (int j = 0; j < 9; j++) {
// 第i行
if (board[i][j] != '.' && !row.add(board[i][j]))
return false;
// 第i列
if (board[j][i] != '.' && !col.add(board[j][i]))
return false;
//
int cubeRow = 3 * (i / 3) + j / 3, cubeCol = 3 * (i % 3) + j % 3;
if (board[cubeRow][cubeCol] != '.' && !cube.add(board[cubeRow][cubeCol]))
return false;
}
}
return true;
}
}
方式2:
public class Solution {
public boolean isValidSudoku(char[][] board) {
for(int i=0;i<9;i++){
int[]flag=new int[10];
for(int j=0;j<9;j++){
if(board[i][j]!='.'){
if(flag[board[i][j]-'0']==0)
flag[board[i][j]-'0']++;
else{
return false;
}
}
}
}
for(int i=0;i<9;i++){
int[]flag=new int[10];
for(int j=0;j<9;j++){
if(board[j][i]!='.'){
if( flag[ board[j][i]-'0' ] ==0)
flag[board[j][i]-'0']++;
else{
return false;
}
}
}
}
for(int i=0 ;i <9;i++){
int[]flag=new int[10];
for(int j=0;j<9;j++){
int left=(i%3)*3+j%3;
int top=((int)i/3)*3+j/3;
if(board[left][top]!='.'){
if( flag[ board[left][top]-'0' ]==0){
flag[ board[left][top]-'0' ]++;
}
else{
return false;
}
}
}
}
return true;
}
}