leetcode做题总结，题目Valid Sudoku 2012/03/03

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数独游戏，横，竖，方框的9个数都不能相同，我的方法是用boolean数组即可。

public class Solution {    public boolean isValidSudoku(char[][] board) {        boolean[] b=new boolean[9];        for(int i=0;i<9;i++){            for(int j=0;j<9;j++){                if(board[i][j]=='.')                    continue;                if(b[Integer.parseInt(board[i][j]+"")-1]==false)                    b[Integer.parseInt(board[i][j]+"")-1]=true;                else                    return false;            }            b=new boolean[9];        }        for(int i=0;i<9;i++){            for(int j=0;j<9;j++){                if(board[j][i]=='.')                    continue;                if(b[Integer.parseInt(board[j][i]+"")-1]==false)                    b[Integer.parseInt(board[j][i]+"")-1]=true;                else                    return false;            }            b=new boolean[9];        }        for(int x=0;x<7;x+=3){            for(int y=0;y<7;y+=3){                for(int i=0;i<3;i++){                    for(int j=0;j<3;j++){                        if(board[x+i][y+j]=='.')                            continue;                        if(b[Integer.parseInt(board[x+i][y+j]+"")-1]==false)                            b[Integer.parseInt(board[x+i][y+j]+"")-1]=true;                        else                            return false;                    }                }                b=new boolean[9];            }        }        return true;            }}

Update 2015/09/30:

public class Solution {    public boolean isValidSudoku(char[][] board) {        if (board.length !=9 || board[0].length !=9) {            return false;        }        for (int i = 0; i < 9; i++){            boolean[] check = new boolean[9];            for (int j = 0; j < 9; j++){                if (board[i][j] == '.')                    continue;                if (check[(int)(board[i][j] - '1')]){                    return false;                }                check[(int)(board[i][j]-'1')] = true;            }        }        for (int j = 0; j < 9; j++){            boolean[] check = new boolean[9];            for (int i = 0; i < 9; i++){                if (board[i][j] == '.')                    continue;                if (check[(int)(board[i][j]- '1')]){                    return false;                }                check[(int)(board[i][j]-'1')] = true;            }        }        for (int i = 0; i < 9; i=i+3){                        for (int j = 0; j < 9; j=j+3){                boolean[] check = new boolean[9];                for (int k = i; k < i+3;k++){                    for (int r = j; r < j+3;r++){                        if (board[k][r] == '.')                            continue;                        if (check[(int)(board[k][r]-'1')]){                            return false;                        }                        check[(int)(board[k][r]-'1')] = true;                    }                }            }        }         return true;           }}

update 2015/10/09: 主要是改变了第三个方格检查，这样就可以使用三个数组一次性扫过检查

public class Solution {    public boolean isValidSudoku(char[][] board) {        if (board.length !=9 || board[0].length !=9) {            return false;        }        for (int i = 0; i < 9; i++){            boolean[] check = new boolean[9];            for (int j = 0; j < 9; j++){                if (board[i][j] == '.')                    continue;                if (check[(int)(board[i][j] - '1')]){                    return false;                }                check[(int)(board[i][j]-'1')] = true;            }        }        for (int j = 0; j < 9; j++){            boolean[] check = new boolean[9];            for (int i = 0; i < 9; i++){                if (board[i][j] == '.')                    continue;                if (check[(int)(board[i][j]- '1')]){                    return false;                }                check[(int)(board[i][j]-'1')] = true;            }        }        for (int i = 0; i < 9; i++){            boolean[] check = new boolean[9];            for (int j = 0; j < 9; j++){                if (board[3 * (i / 3) + (j / 3)][3 * (i % 3) + (j % 3)] == '.')                    continue;                if (check[board[3 * (i / 3) + (j / 3)][3 * (i % 3) + (j % 3)] - '1'])                    return false;                check[board[3 * (i / 3) + (j / 3)][3 * (i % 3) + (j % 3)] - '1'] = true;            }        }        return true;    }}

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