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.
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 // Note: The Solution object is instantiated only once and is reused by each test case. 4 if(board == null || board.length != 9 || board[0].length != 9) return false; 5 int[] checkr = new int[9]; 6 int[] checkc = new int[9]; 7 for(int i = 0; i < 9; i ++){ 8 for(int j = 0; j < 9; j ++){ 9 if(board[i][j] - '0' > 0 && board[i][j] - '0' < 10){ 10 checkr[board[i][j] - '0' - 1] ++; 11 } 12 if(board[j][i] - '0' > 0 && board[j][i] - '0' < 10){ 13 checkc[board[j][i] - '0' - 1] ++; 14 } 15 } 16 for(int ii = 0; ii < 9; ii ++){ 17 if(checkr[ii] > 1 || checkc[ii] > 1){ 18 return false; 19 } 20 } 21 checkr = new int[9]; 22 checkc = new int[9]; 23 } 24 for(int i = 0; i < 9; i ++){ 25 for(int j = 0; j < 3; j ++){ 26 if(board[i][j] != '.') 27 checkc[board[i][j] - '0' - 1] ++; 28 } 29 if((i + 1) % 3 == 0){ 30 for(int ii = 0; ii < 9; ii ++){ 31 if(checkr[ii] > 1 || checkc[ii] > 1){ 32 return false; 33 } 34 } 35 checkc = new int[9]; 36 } 37 } 38 39 checkc = new int[9]; 40 for(int i = 0; i < 9; i ++){ 41 for(int j = 3; j < 6; j ++){ 42 if(board[i][j] != '.') 43 checkc[board[i][j] - '0' - 1] ++; 44 } 45 if((i + 1) % 3 == 0){ 46 for(int ii = 0; ii < 9; ii ++){ 47 if(checkr[ii] > 1 || checkc[ii] > 1){ 48 return false; 49 } 50 } 51 checkc = new int[9]; 52 } 53 } 54 55 checkc = new int[9]; 56 for(int i = 0; i < 9; i ++){ 57 for(int j = 6; j < 9; j ++){ 58 if(board[i][j] != '.') 59 checkc[board[i][j] - '0' - 1] ++; 60 } 61 if((i + 1) % 3 == 0){ 62 for(int ii = 0; ii < 9; ii ++){ 63 if(checkr[ii] > 1 || checkc[ii] > 1){ 64 return false; 65 } 66 } 67 checkc = new int[9]; 68 } 69 } 70 71 return true; 72 } 73 }
第二遍：
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 // Note: The Solution object is instantiated only once and is reused by each test case. 4 if(board == null || board.length != 9 || board[0].length != 9) return false; 5 boolean[] checkr = new boolean[9]; 6 boolean[] checkc = new boolean[9]; 7 for(int i = 0; i < 9; i ++){ 8 checkr = new boolean[9]; 9 checkc = new boolean[9]; 10 for(int j = 0; j < 9; j ++){ 11 if ( board[i][j] != '.'){ 12 if(checkr[board[i][j] - '1']) return false; 13 checkr[board[i][j] - '1'] = true; 14 } 15 if ( board[j][i] != '.'){ 16 if(checkc[board[j][i] - '1']) return false; 17 checkc[board[j][i] - '1'] = true; 18 } 19 } 20 } 21 for(int a = 0; a < 3; a ++){ 22 for(int b = 0; b < 3; b ++){ 23 checkr = new boolean[9]; 24 for(int i = a * 3; i < (a + 1) * 3; i ++){ 25 for(int j = b * 3; j < (b + 1) *3; j ++){ 26 if ( board[i][j]!='.' ){ 27 if(checkr[board[i][j] - '1']) return false; 28 checkr[board[i][j] - '1'] = true; 29 } 30 } 31 } 32 } 33 } 34 return true; 35 } 36 }
第三遍：
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 if(board == null || board.length != 9 || board[0].length != 9) return false; 4 boolean[] value = new boolean[9]; 5 for(int i = 0; i < 9; i ++){ 6 value = new boolean[9]; 7 for(int j = 0; j < 9; j ++){ 8 if(board[i][j] != '.' && value[board[i][j] - '1']) return false; 9 else if(board[i][j] != '.' && !value[board[i][j] - '1']) value[board[i][j] - '1'] = true; 10 } 11 value = new boolean[9]; 12 for(int j = 0; j < 9; j ++){ 13 if(board[j][i] != '.' && value[board[j][i] - '1']) return false; 14 else if(board[j][i] != '.' && !value[board[j][i] - '1']) value[board[j][i] - '1'] = true; 15 } 16 } 17 for(int k = 0; k < 3; k ++){ 18 for(int h = 0; h < 3; h ++){ 19 value = new boolean[9]; 20 for(int i = 3*k; i < 3*k + 3; i ++){ 21 for(int j = 3*h; j < 3*h + 3; j ++){ 22 if(board[i][j] != '.' && value[board[i][j] - '1']) return false; 23 else if(board[i][j] != '.' && !value[board[i][j] - '1']) value[board[i][j] - '1'] = true; 24 } 25 } 26 } 27 } 28 return true; 29 } 30 }