Submission #2502258

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Source Code Expand

#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
using namespace std;

void solve (set<string> &orders, string header, map<char, vector<int>> &candidates, string &base, int n, int k)
{
	for (auto &candidate : candidates)
	{
		auto &v = candidate.second;

		orders.insert(header + candidate.first);
		if (k <= orders.size()) break;

		map<char, vector<int>> candy;
		for (auto i : v)
		{
			if (i+1 < n) candy[base[i+1]].push_back(i+1);
		}

		solve(orders, header + candidate.first, candy, base, n, k);
	}

	return;
}
int main ()
{
	string s;
	cin >> s;
	int n = s.size();

	int k;
	cin >> k;

	map<char, vector<int>> candidates;
	for (int i=0; i<n; ++i)
	{
		candidates[s[i]].push_back(i);
	}
	set<string> orders;

	solve(orders, "", candidates, s, n, k);

	for (auto sub : orders)
	{
		if (0 == --k)
		{
			cout << sub << endl;
			break;
		}
	}

	
	return 0;
}

Submission Info

Judge Result