movingCount.cpp

// 13 机器人🤖的运动范围

#include "array_util.h"
using namespace std;

// 辅助函数 计算各十进制位之和
int getDigitSum(int num)
{
    assert(num >= 0);
    int sum = 0;
    while (num) {
        sum += num % 10;
        num /= 10;
    }
    return sum;
}

int check(int threshold, int rows, int cols, int row, int col, bool* visited)
{
    if (row >= 0 && row < rows && col >= 0 && col < cols
        && getDigitSum(row) + getDigitSum(col) <= threshold
        && !visited[row + cols + col])
        return true;
    return false;
}

int movingCountCore(int threshold, int rows, int cols, int row, int col, bool* 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, col - 1, visited)
            + movingCountCore(threshold, rows, cols, row + 1, col, visited)
            + movingCountCore(threshold, rows, cols, row, col + 1, visited);
    }
    return count;
}

int movingCount(int threshold, int rows, int cols)
{
    if (threshold < 0 || rows <= 0 || cols <= 0)
        return 0;

    bool* visited = new bool[rows * cols];
    for (int i = 0; i < rows * cols; i++) {
        visited[i] = false;
    }

    int count = movingCountCore(threshold, rows, cols, 0, 0, visited);

    delete[] visited;

    return count;
}