LeetCode35:Valid Sudoku

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.

public class Solution {    public boolean isValidSudoku(char[][] board) {        // Start typing your Java solution below        // DO NOT write main() function        int [][] table=new int[27][9];        int [][] squareIndex = new int [][] {{0,1,2}, {3,4,5}, {6,7,8}};        for(int i=0; i<9; i++){ // rows            for(int j=0; j<9; j++){ // cols                if(board[i][j]=='.')                    continue;                if(!Character.isDigit(board[i][j]))                    return false;                int val = Character.getNumericValue(board[i][j]);                // Rows                if(table[i][val-1]!=0)                    return false;                table[i][val-1]=1;                // Columns                if(table[j+9][val-1]!=0)                    return false;                table[j+9][val-1]=1;                // Squares                int sNdx = squareIndex[i/3][j/3];                if(table[sNdx+18][val-1]!=0)                    return false;                table[sNdx+18][val-1]=1;            }        }        return true;    }}

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LL's solution:

空间是O(N)时间是O(N*sqrt(N))

public class Solution {    public void reset(HashMap<Character,Boolean> sequence){        sequence.put('1',false);        sequence.put('2',false);        sequence.put('3',false);        sequence.put('4',false);        sequence.put('5',false);        sequence.put('6',false);        sequence.put('7',false);        sequence.put('8',false);        sequence.put('9',false);    }    public boolean isValidSudoku(char[][] board) {        // Start typing your Java solution below        // DO NOT write main() function        boolean res = true;        HashMap<Character,Boolean> sequence = new HashMap<Character,Boolean>();                 //check horizon        if(res==true){            for(int row = 0;row<9;row++){                if(res==true){                    reset(sequence);                     for(int col = 0;col<9;col++){                        char c = board[row][col];                        if(c=='.')                            continue;                        else{                            if(sequence.get(c)==false)                                sequence.put(c,true);                            else{                                res = false;                                break;                            }                        }                    }                }                else                    break;            }        }                //check vertical         if(res==true){            for(int col = 0;col<9;col++){                if(res==true){                    reset(sequence);                     for(int row = 0;row<9;row++){                        char c = board[row][col];                        if(c=='.')                            continue;                        else{                            if(sequence.get(c)==false)                                sequence.put(c,true);                            else{                                res = false;                                break;                            }                        }                    }                }                else                    break;            }        }                //check square        int row_base = 0,col_base = 0;        if(res==true){            while(row_base<9 || col_base<9){                if(res == true){                    reset(sequence);                    for(int row = row_base;row<row_base+3;row++){                        if(res==true){                             for(int col = col_base;col<col_base+3;col++){                                char c = board[row][col];                                if(c=='.')                                    continue;                                else{                                    if(sequence.get(c)==false)                                        sequence.put(c,true);                                    else{                                        res = false;                                        break;                                    }                                }                            }                        }//end if                        else                            break;                    }//end for                    col_base += 3;                    if(col_base == 9 && row_base<9){                        if(row_base!=6)                            col_base = 0;                        row_base += 3;                    }                }//end if            }//end while        }//end if                return res;            }}

Note:

记得处理最后row_base = 6,col_base = 9时，不能把col_base重新置0.

时空转换，时间O(N)，空间O(N*sqrt(N))

public class Solution {    public boolean isValidSudoku(char[][] board) {        // Start typing your Java solution below        // DO NOT write main() function        boolean res = true;        //HashMap<Character,Boolean> sequence = new HashMap<Character,Boolean>();         boolean[][] valid = new boolean[27][9];        int horizen = 0;        int vertical = 9;        int square = 18;        int index,sq_index;        for(int row = 0; row<9; row++){            if(res){                for(int col = 0; col<9; col++){                    char c = board[row][col];                    if(c=='.')                        continue;                    else{                        index = Character.getNumericValue(c)-1;                        //check horizen                        if(valid[horizen+row][index]==false)                            valid[horizen+row][index]=true;                        else{                            res = false;                            break;                        }                        //check vertical                        if(valid[vertical+col][index]==false)                            valid[vertical+col][index] = true;                        else{                            res = false;                            break;                        }                        //check suqare                        sq_index = 3*((int)row/3) + (int)col/3;                        if(valid[square+sq_index][index]==false)                            valid[square+sq_index][index] = true;                        else{                            res = false;                            break;                        }                    }                }                        }            else                break;        }               return res;            }}