标签：java   leetcode   sudoku   

题目

方法

典型的回溯法解决数独问题。使用递归来求解。

	private boolean isValidSudoku(char[][] board, int row, int col) {
		int len = 9;
		for (int i = 0; i < len; i++) {
			if (i != row) {
				if (board[row][col] == board[i][col]) {
					return false;
				}
			}
		}
		for (int j = 0; j < len; j++) {
			if (j != col) {
				if (board[row][col] == board[row][j]) {
					return false;
				}
			}
		}
		int curRowStart = (row / 3) * 3;
		int curColStart = (col / 3) * 3;
		
		for (int i = curRowStart; i < curRowStart + 3; i++) {
			for (int j = curColStart; j < curColStart + 3; j++) {
				if (!(i == row && j == col)) {
					if (board[i][j] == board[row][col]) {
						return false;
					}
				}
			}
		}
		return true;
	}
	
	private boolean recallSudoku(char[][] board) {
    	int len = 9;
        for (int i = 0; i < len; i++) {
        	for (int j = 0; j < len; j++) {
        		if (board[i][j] == '.') {
        			
        			for (int k = 0; k < len; k++) {
        				board[i][j] = (char)('1' + k);
        				
        				if (isValidSudoku(board, i, j)) {
        					if (recallSudoku(board)){
        						return true;
        					}
        				}
        				board[i][j] = '.';
        			}       			
        			return false;       			
        		}
        	}
        }
        return true;
	}
	
    public void solveSudoku(char[][] board) {
    	recallSudoku(board);
    }

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Sudoku Solver

标签：java   leetcode   sudoku   

原文地址：http://blog.csdn.net/u010378705/article/details/34855619