[BOJ]15655 NとN(6)(逆トラッキング)

1.質問

2.解法

1) ⭕RIGHT⭕

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int N, M;
vector<int> input;
vector<int> v;
bool visited[8];

void backtracking(int level)
{
	if (level == M)
	{
		for (int i = 0; i < v.size(); ++i)
			cout << v[i] << ' ';
		cout << '\n';
		return;
	}
	for (int i = 1; i <= N; ++i)
	{
		if (!visited[i]) {
			if (v.empty() || input[i] >= v.back()) {
				visited[i] = true;
				v.push_back(input[i]);
				backtracking(level + 1);
				v.pop_back();
				visited[i] = false;
			}
		}
	}
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(NULL); cout.tie(NULL);

	cin >> N >> M;
	input.push_back(0);
	for (int i = 0; i < N; ++i)
	{
		int tmp;
		cin >> tmp;
		input.push_back(tmp);
	}
	sort(input.begin(), input.end());

	backtracking(0);
	
	return 0;
}