标签:style blog class code java tar
犯了很多细节上的错误,比如忽视了“-”的存在,正是因为有“-”的存在,所以不能用if (rows.size() == i)来判断rows里面是否已经存某一行,如果不存在再row = new ArrayList<Character>(); row.add(board[i][j]);rows.add(row);来添加新的一行。所以只能一开头就不辞辛苦地建一个ArrayList<ArrayList<Character>> rows,再循环九次向里面添加9个空的ArrayList<Character> row
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 ArrayList<ArrayList<Character>> rows = new ArrayList<ArrayList<Character>>(); 4 ArrayList<ArrayList<Character>> columns = new ArrayList<ArrayList<Character>>(); 5 ArrayList<ArrayList<Character>> boxes = new ArrayList<ArrayList<Character>>(); 6 ArrayList<Character> row, column, box; 7 for (int r=0; r<9; r++){ 8 row = new ArrayList<Character>(); 9 rows.add(row); 10 } 11 for (int c=0; c<9; c++){ 12 column = new ArrayList<Character>(); 13 columns.add(column); 14 } 15 for (int b=0; b<9; b++){ 16 box = new ArrayList<Character>(); 17 boxes.add(box); 18 } 19 for (int i=0; i<9; i++){ 20 for (int j=0; j<9; j++){ 21 if (board[i][j]>‘9‘ || board[i][j]<‘1‘) continue; 22 23 // check rows 24 row = rows.get(i); 25 if (row.contains(board[i][j])) return false; 26 else row.add(board[i][j]); 27 28 // check columns 29 column = columns.get(j); 30 if (column.contains(board[i][j])) return false; 31 else column.add(board[i][j]); 32 33 // check boxes 34 int boxnum = getboxnum(i, j); 35 box = boxes.get(boxnum); 36 if (box.contains(board[i][j])) return false; 37 else box.add(board[i][j]); 38 } 39 } 40 return true; 41 42 } 43 44 public int getboxnum(int i, int j){ 45 int column = 0; 46 int row = 0; 47 if (i>=0 && i<=2) row = 1; 48 if (i>=3 && i<=5) row = 2; 49 if (i>=6 && i<=8) row = 3; 50 if (j>=0 && j<=2) column = 1; 51 if (j>=3 && j<=5) column = 2; 52 if (j>=6 && j<=8) column = 3; 53 return (row-1)*3 + column - 1; 54 } 55 56 }
看到一个不错的方法:
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 // Start typing your Java solution below 4 // DO NOT write main() function 5 int N = board.length; 6 int[] rows = new int[N]; 7 int[] cols = new int[N]; 8 int[] cubes = new int[N]; 9 10 for(int i=0;i<N;i++) 11 for(int j=0;j<N;j++){ 12 if(board[i][j]!=‘.‘){ 13 int b = (i/3)*3+j/3; 14 int offset = board[i][j] - ‘1‘; 15 16 if(offset>8 || offset<0) return false; 17 if((rows[i] & (1<<offset))!=0) return false; 18 if((cols[j] & (1<<offset))!=0) return false; 19 if((cubes[b] & (1<<offset))!=0) return false; 20 21 rows[i] |= 1 << offset; 22 cols[j] |= 1 << offset; 23 cubes[b] |= 1 << offset; 24 25 } 26 } 27 return true; 28 } 29 }
Leetcode: Valid Sudoku,布布扣,bubuko.com
标签:style blog class code java tar
原文地址:http://www.cnblogs.com/EdwardLiu/p/3719965.html