【经典】【DP】计算得分的排列方式和组合方式

//得到分数k的组合方式
int count_combination(const int k, const vector<int> &W)
{
	if (W.empty())
		return -1;
	vector<int> combination(k + 1, 0);
	combination[0] = 1;//一种方式达到0
	for (int i = 0; i < W.size(); i++)
	{
		int score = W[i];
		for (int j = score; j <= k; j++)
			combination[j] += combination[j - score];
	}
	return combination[k];
}

//得到分数k的排列方式
int count_permutation(const int k, const vector<int> &W)
{
	if (W.empty())
		return -1;
	vector<int> permutation(k + 1, 0);
	permutation[0] = 1;//一种方式达到0
	for (int i = 0; i <= k; i++)
	{
		for (int j = 0;j < W.size(); j++)
		{
			if (i >= W[j])
				permutation[i] += permutation[i - W[j]];
		}
	}
	return permutation[k];
}