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.
Note:
A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 for (int i=0; i<9; i++) { 4 if (!isParticallyValid(board,i,0,i,8)) return false; 5 if (!isParticallyValid(board,0,i,8,i)) return false; 6 } 7 for (int i=0;i<3;i++){ 8 for(int j=0;j<3;j++){ 9 if (!isParticallyValid(board,i*3,j*3,i*3+2,j*3+2)) return false; 10 } 11 } 12 return true; 13 } 14 private boolean isParticallyValid(char[][] board, int x1, int y1,int x2,int y2){ 15 Set singleSet = new HashSet(); 16 for (int i= x1; i<=x2; i++){ 17 for (int j=y1;j<=y2; j++){ 18 if (board[i][j]!=‘.‘) if(!singleSet.add(board[i][j])) return false; // If this set already contains the element, the call leaves the set unchanged and returns false. 19 } 20 } 21 return true; 22 } 23 24 }
https://leetcode.com/discuss/17990/sharing-my-easy-understand-java-solution-using-set
原文：http://www.cnblogs.com/hygeia/p/5074821.html