暴搜 剪枝

枚举固定的位置

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e3+10;
int n,k;
int res;
void dfs(int last,int sum,int cur){if(cur==k){if(sum==n)res++;return;}for(int i=last;i+sum<=n;i++)dfs(i,sum+i,cur+1);
}
int main()
{cin>>n>>k;dfs(1,0,0);cout<<res;
}