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  • 剑指Offer(书):机器人的运动范围

    题目:地上有一个m行和n列的方格。一个机器人从坐标0,0的格子开始移动,每一次只能向左,右,上,下四个方向移动一格,但是不能进入行坐标和列坐标的数位之和大于k的格子。 例如,当k为18时,机器人能够进入方格(35,37),因为3+5+3+7 = 18。但是,它不能进入方格(35,38),因为3+5+3+8 = 19。请问该机器人能够达到多少个格子?

    分析:递归还是薄弱点啊。一深入一些脑子就乱了。

    public int movingCount(int threshold, int rows, int cols) {
        if (threshold < 0 || rows < 0 || cols < 0) {
            return 0;
        }
        boolean[] visited = new boolean[rows * cols];
        int count = movingCountCore(threshold, rows, cols, 0, 0, visited);
        return count;
    
    }
    
    private int movingCountCore(int threshold, int rows, int cols, int row, int col, boolean[] visited) {
        int count = 0;
        if (check(threshold, rows, cols, row, col, visited)) {
            visited[row * cols + col] = true;
            count = 1 + movingCountCore(threshold, rows, cols, row + 1, col, visited)
                    + movingCountCore(threshold, rows, cols, row - 1, col, visited)
                    + movingCountCore(threshold, rows, cols, row, col + 1, visited)
                    + movingCountCore(threshold, rows, cols, row, col - 1, visited);
        }
        return count;
    }
    
    private boolean check(int threshold, int rows, int cols, int row, int col, boolean[] visited) {
        if (row >= 0 && row < rows && col >= 0 && col < cols
                && getDigitSum(row) + getDigitSum(col) <= threshold
                && !visited[row * cols + col]) {
            return true;
        }
        return false;
    }
    
    private int getDigitSum(int number) {
        int sum = 0;
        while (number > 0) {
            sum += number % 10;
            number /= 10;
        }
        return sum;
    }
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  • 原文地址:https://www.cnblogs.com/liter7/p/9431544.html
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