37. 解数独

最新推荐文章于 2024-12-16 10:07:47 发布

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最新推荐文章于 2024-12-16 10:07:47 发布

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本文链接：https://blog.youkuaiyun.com/weixin_39590058/article/details/119668628

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这篇博客深入探讨了如何使用递归方法解决数独问题，通过`solveSudoku`函数实现核心逻辑，并介绍了`isValid`函数用于检查单元格合法性。通过`board`二维字符数组，逐步填充数字并确保遵循数独规则。

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public void solveSudoku(char[][] board) {
        
        if (board.length == 0 || board[0].length == 0) return;
        solve(board);
    }

    private boolean solve(char[][] board) {
        for (int i = 0; i < board.length; i++) {
            for (int j = 0; j < board[0].length; j++) {
                if (board[i][j] != '.') continue;

                for (char c = '1'; c <= '9'; c++) {
                    if (!isValid(board, i, j, c)) continue;
                    board[i][j] = c;

                    if (solve(board)) return true;
                    else              board[i][j] = '.';
                }
                return false;
            }
        }
        return true;
    }

    private boolean isValid(char[][] board, int row, int col, char c) {
        for (int i = 0; i < 9; i++) {
            if (board[row][i] == c) return false;
            if (board[i][col] == c) return false;
            int cellR = (row / 3) * 3 + i / 3;
            int cellC = (col / 3) * 3 + i % 3;
            if (board[cellR][cellC] == c) return false;
        }
        return true;
    }