题解 | #放苹果#

#include<iostream>
using namespace std;


int m,n;

int dfs(int u,int sum,int last)
{
	if(u == n){
		if(sum == 0) return 1;
		else return 0;
	}
	
	int res = 0;
	for(int i = last;i <= sum;i++)
	{
		res += dfs(u + 1,sum - i,i); 
	}
	return res;
}

int main(void)
{
	
	cin >> m >> n;
	cout << dfs(0,m,0) << endl;
	
	
	return 0;
}