Submission #1627617

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Source Code Expand

#include "bits/stdc++.h"
#include <sys/timeb.h>
#include <fstream>

using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define replrev(i,a,b) for(int i=(int)(b)-1;i>=(int)(a);i--)
#define reprev(i,n) replrev(i,0,n)
#define repi(itr,ds) for(auto itr=ds.begin();itr!=ds.end();itr++)
#define all(a) a.begin(),a.end()
#define mp make_pair
#define mt make_tuple
#define INF 2000000000
#define INFL 1100000000000000000LL
#define EPS (1e-10)
#define MOD 1000000007
#define PI 3.1415926536
#define RMAX 4294967295

typedef long long ll;
typedef pair<int, int> P;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<P> vP;
typedef vector<vector<int> > vvi;
typedef vector<vector<bool> > vvb;
typedef vector<vector<ll> > vvll;
typedef vector<vector<char> > vvc;
typedef vector<vector<string> > vvs;
typedef vector<vector<double> > vvd;
typedef vector<vector<P> > vvP;
typedef priority_queue<int, vector<int>, greater<int> > pqli;
typedef priority_queue<ll, vector<ll>, greater<ll> > pqlll;
typedef priority_queue<P, vector<P>, greater<P> > pqlP;
typedef pair<int, pair<int, int> > Edge;
typedef vector<Edge> vE;
typedef priority_queue<Edge, vector<Edge>, greater<Edge> > pqlE;

string debug_show(P a) {
	return "(" + to_string(a.first) + "," + to_string(a.second) + ")";
}


int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	string s;
	ll K;
	cin >> s >> K;

	ll N = s.length();
	ll cur = 0;
	
	vector<stack<pair<ll, int>>> place(26);

	vll num(N), sum(N);
	num[N - 1] = 1;
	sum[N - 1] = 1;
	place[s[N - 1] - 'a'].push(mp(1, N - 1));

	reprev(i, N - 1) {
		num[i] = min(INFL, sum[i + 1] + 1);
		sum[i] = num[i] + sum[i + 1];
		if (!place[s[i] - 'a'].empty())sum[i] -= place[s[i] - 'a'].top().first;
		sum[i] = min(INFL, sum[i]);
		place[s[i] - 'a'].push(mp(num[i], i));
	}

	//rep(i, N)cout << num[i] << " "; cout << endl;
	//rep(i, N)cout << sum[i] << " "; cout << endl;

	ll maxsize = 0;
	rep(i, 26) {
		if (place[i].empty())continue;
		maxsize += place[i].top().first;
		maxsize = min(INFL, maxsize);
	}
	if (K > maxsize) {
		cout << "Eel" << endl;
		return 0;
	}

	string ans = "";

	while (K > 0) {
		K--;
		ll next = 0;
		rep(i, 26) {
			if (place[i].empty())continue;
			if (K - place[i].top().first < 0) {
				next = place[i].top().second + 1;
				ans += (char)('a' + i);
				break;
			}
			K -= place[i].top().first;
		}
		while (cur < next) {
			place[s[cur] - 'a'].pop();
			cur++;
		}
	}

	if (ans.size() == 0) {
		cout << "Eel" << endl;
	}
	else {
		cout << ans << endl;
	}

	return 0;
}

Submission Info

Judge Result