[leetcode] Valid Sudoku

最新推荐文章于 2019-05-09 19:49:06 发布

原创最新推荐文章于 2019-05-09 19:49:06 发布 · 330 阅读

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本文提供了一种检查数独是否有效的算法实现。通过使用C++和Java代码示例，介绍了如何确保数独板上的行、列及每个宫格内数字1-9不重复出现的方法。

From : https://leetcode.com/problems/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 '.'.

只要不重复出现即可。

A partially filled sudoku which is valid.

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        // **
        set<int> box;
        char ch;
        for(int i=0; i<9; i++) {
            box.clear();
            for(int j=0; j<9; j++) {
                ch = board[i][j];
                if(ch != '.' && box.find(ch)!=box.end()) {
                    return false;
                } else if(ch != '.') {
					box.insert(ch);
                }
            }
        }
        // **
        for(int j=0; j<9; j++) {
            box.clear();
            for(int i=0; i<9; i++) {
                ch = board[i][j];
                if(ch != '.' && box.find(ch)!=box.end()) {
                    return false;
                } else if(ch != '.') {
                    box.insert(ch);
                }
            }
        }
        // **
        for(int i=0; i<3; i++) {
            for(int j=0; j<3; j++) {
                box.clear();
                for(int k=i*3; k<(i+1)*3;k++) {
                    for(int t=j*3; t<(j+1)*3;t++) {
                        ch = board[k][t];
                        if(ch != '.' && box.find(ch)!=box.end()) {
                            return false;
                        } else if(ch != '.') {
                            box.insert(ch);
                        }
                    }
                }
            }
        }
        return true;
    }
};

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
		vector<vector<bool>> rows(9, vector<bool>(9,false));
		vector<vector<bool>> cols(9, vector<bool>(9,false));
		vector<vector<bool>> blocks(9, vector<bool>(9,false));

		for(int i = 0; i < 9; i++)
			for(int j = 0; j < 9; j++) {
				if(board[i][j] == '.')continue;
				int num = board[i][j] - '1';
				if(rows[i][num] || cols[j][num] || blocks[i - i%3 + j/3][num])
					return false;
				rows[i][num] = cols[j][num] = blocks[i - i%3 + j/3][num] = true;
			}
		return true;
    }
};

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