面试题67：机器人的运动范围

题目：地上有一个M行N列的方格，一个机器人从坐标（0，0）的格子开始移动，它每一次可以向上下左右移动一格，但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+7+3=18。但它不能进入方格（35,38），因为3+5+3+8=19。请问机器人能够到达多少个格子？

#include <stdio.h>

int getDigitSum(int number)
{
int sum = 0;
while(number > 0)
{
sum += number % 10;
number /= 10;
}

return sum;
}

bool 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)
{
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;
}

from:

https://github.com/zhedahht/ChineseCodingInterviewAppendix/tree/master/RobotMove