此代码疑似AI生成，请仔细甄别

笑点解析：现在才知道 vector 迭代器可以直接减，不需要 distance

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;
int a[25];
vector <int> states;
void solve(){
	int n, m;
	cin >> n >> m;
	for(int i = 0; i < n; i++) cin >> a[i];
	for(int i = 1; i < (1 << n); i++){
		int cur = 0, ct = 0;
		for(int j = 0; j < n; j++){
			if(i >> j & 1) cur += a[j], ct++;
		}
		if(ct == m) states.push_back(cur);
	}
	sort(states.begin(), states.end());
	auto it = unique(states.begin(), states.end());
	cout << distance(states.begin(), it) << '\n';
	for(int i = 0; i < n; i++) a[i] = 0;
	states.clear();
}
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
	int t;
	cin >> t;
	while(t--) solve();

	return 0;
}