[검지offer] 소급법

// ， 
#include
#include
using namespace std;

// 
bool haspathcore( char* m, int row, int col, int i, int j, const char* str, int& pathlen, bool* vis)
{
	if (str[pathlen] == '\0')
	{
		return true;
	}
	bool haspath = false;
	if (i >= 0 && i < row && j >= 0 && j < col && m[i*col + j] == str[pathlen] && !vis[i*col + col])
	{
		++pathlen;
		vis[i*col + j] = true;

		haspath = haspathcore(m, row, col, i + 1, j, str, pathlen, vis) ||
			haspathcore(m, row, col, i - 1, j, str, pathlen, vis) ||
			haspathcore(m, row, col, i, j + 1, str, pathlen, vis) ||
			haspathcore(m, row, col, i, j - 1, str, pathlen, vis);

		if (!haspath)
		{
			--pathlen;
			vis[i*col + j] = false;
		}
	}
	return haspath;

}
// 
bool haspath( char* m, int row, int col, const char* str)
{
	if (str == NULL || m == NULL || row < 1 || col < 1)
	{
		return false;
	}

	bool *vis = new bool[row*col];
	memset(vis, 0, row*col);

	int pathlen = 0;
	for (int i = 0; i < row; i++)
	{
		for (int j = 0; j < col; j++)
		{
			if (haspathcore(m, row, col, i, j, str, pathlen, vis))
			{
				delete[] vis;
				return true;
			}
		}
	}
	
	return false;
}
 
int main()
{
	char test[] = "abtgcfcsjdeh";
	char str[] = "bt";
	bool resu = haspath(test, 3, 4, str);
	cout << resu << endl;
	getchar();
	return 0;
	 
	 
}

#include
using namespace std;
// 
int getDigitSum(int num)
{
	int sum = 0;
	while (num > 0)
	{
		sum += num % 10;
		num /= 10;
	}
	return sum;
}

// 
bool check(int threshold, int row, int col, int i, int j, bool* vis)
{
	if (i >= 0 && i < row&&j >= 0 && j < col&&getDigitSum(i) + getDigitSum(j) <= threshold && !vis[i*col + j])
	{
		return true;
	}
	return false;
}

// 
int movingCountCore(int threshold, int row, int col, int i, int j, bool* vis)
{
	int count = 0;
	if (check(threshold, row, col, i, j, vis))
	{
		vis[i*col + j] = true;
		count = 1 + movingCountCore(threshold, row, col, i + 1, j, vis)
			+ movingCountCore(threshold, row, col, i - 1, j, vis)
			+ movingCountCore(threshold, row, col, i, j + 1, vis)
			+ movingCountCore(threshold, row, col, i, j - 1, vis);
	}
	return count;
}

// 
int movingCount(int threshold, int row, int col)
{
	if (threshold < 0 || row <= 0 || col <= 0)
	{
		return 0;
	}
	bool* vis = new bool[row*col];
	for (int i = 0; i < row*col; i++)
	{
		vis[i] = false;
		
	}
	int count = movingCountCore(threshold, row, col, 0, 0, vis);
	delete[] vis;
	return count;
}

int main()
{
	 
	int count = movingCount(5, 4, 4);
	cout << "count= " << count << endl;
	getchar();
	return 0;
}