Submission #296129

#	Time	Username	Problem	Language	Result	Execution time	Memory
296129		RealSuperman1	Roller Coaster Railroad (IOI16_railroad)	C++14	64 / 100	265 ms	19992 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define fi first
#define se second
#define pll pair<long long, long long>
#define pii pair<int, int>

using namespace std;

const ll INF = 1e18;

int n;

bool cmp(pii x, pii y) {
	return x.fi > y.fi;
}

ll case3(vector <int> s, vector <int> t) {
	vector <pii> t1(n);
	for (int i = 0; i < n; i++)
		t1[i] = {t[i], i};
	sort(t1.begin(), t1.end(), cmp);
//	for (auto to : s1)
//		cout << to.fi << " " << to.se << endl;
//	cout << endl;
//	return 0;
	vector <int> nx(n, -1);
	set <pii> sn = {};
	for (int i = 0; i < n; i++)
		sn.insert({s[i], i});
	set <pii>::iterator it;
	for (int i = 0; i < n; i++) {
		it = sn.lower_bound({t1[i].fi, 0});
		if (it == sn.end())
			continue;
		pii val = *it;
		if (val.se == t1[i].se)
			it = sn.upper_bound(val);
		if (it == sn.end())
			continue;
		val = *it;
		nx[t1[i].se] = val.se;
//		cout << t1[i].se << "->" << val.se << endl;
		sn.erase(it);
		if (sn.size() == 1)
			break;
	}
	if (sn.size() == 1)
		return 0ll;
	vector <ll> s_new, t_new;
	for (set<pii>::iterator it = sn.begin(); it != sn.end(); it++) {
		int curt, curs;
		pii val = *it;
		int u = val.se;
		curs = s[u];
		while (nx[u] != -1)
			u = nx[u];
		curt = t[u];
		s_new.pb(curs * 1ll);
		t_new.pb(curt * 1ll);
	}
	ll ans = 0, sumt = 0, sums = 0;
	for (int i = 0; i < s_new.size(); i++) {
//		cout << s_new[i] << " ";
		sums += s_new[i] * 1ll;
	}
//	cout << endl;
	pll mx1 = {-1, -1}, mx2 = {-1, -1};
	for (int i = 0; i < t_new.size(); i++) {
//		cout << t_new[i] << " ";
		sumt += t_new[i] * 1ll;
		if (t_new[i] >= mx1.fi) {
			mx2 = mx1;
			mx1 = {t_new[i], i};
		} else if (t_new[i] >= mx2.fi)
			mx2 = {t_new[i], i};
	}
//	cout << endl;
	ll mn = INF;
	for (int i = 0; i < s_new.size(); i++) {
		if (mx1.se != i)
			mn = min(mn, s_new[i] * 1ll - mx1.fi * 1ll);
		else
			mn = min(mn, s_new[i] * 1ll - mx2.fi * 1ll);
	}
//	cout << mx1.fi << " " << mx1.se << endl;
//	cout << mx2.fi << " " << mx2.se << endl;
	return sumt - sums + mn;
}

ll plan_roller_coaster(vector <int> s, vector <int> t) {
	n = s.size();
	if (n > 16) {
		return case3(s, t);
	}
	vector < vector <ll> > w;
	vector < vector <ll> > dp;
	w.resize(n);
	for (int i = 0; i < n; i++) {
		w[i].resize(n);
		for (int j = 0; j < n; j++) {
			if (i == j)
				continue;
			w[i][j] = max(0, t[i] - s[j]); 
		}
	}
	dp.resize((1 << n));
	for (int mask = 0; mask < (1 << n); mask++) {
		dp[mask].resize(n);
		for (int i = 0; i < n; i++)
			dp[mask][i] = INF;
	}
	for (int i = 0; i < n; i++)
		dp[0][i] = 0;
	vector <int> b;
	for (int mask = 1; mask < (1 << n); mask++) {
		b.clear();
		for (int i = 0; i < n; i++)
			if (1 & (mask >> i))
				b.pb(i);
		if (b.size() == 1) {
			dp[mask][b[0]] = 0;
			continue;
		}
		for (int i = 0; i < b.size(); i++)
			for (int j = 0; j < b.size(); j++) {
				if (i == j)
					continue;
				int mask1 = (mask ^ (1 << b[i]));
				dp[mask][b[i]] = min(dp[mask][b[i]], dp[mask1][b[j]] + w[b[j]][b[i]]);
			}
	}
	ll ans = INF;
	for (int i = 0; i < n; i++)
		ans = min(ans, dp[(1 << n) - 1][i]);
	return ans;
}

Compilation message (stderr)

railroad.cpp: In function 'long long int case3(std::vector<int>, std::vector<int>)':
railroad.cpp:65:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |  for (int i = 0; i < s_new.size(); i++) {
      |                  ~~^~~~~~~~~~~~~~
railroad.cpp:71:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |  for (int i = 0; i < t_new.size(); i++) {
      |                  ~~^~~~~~~~~~~~~~
railroad.cpp:82:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   82 |  for (int i = 0; i < s_new.size(); i++) {
      |                  ~~^~~~~~~~~~~~~~
railroad.cpp:64:5: warning: unused variable 'ans' [-Wunused-variable]
   64 |  ll ans = 0, sumt = 0, sums = 0;
      |     ^~~
railroad.cpp: In function 'long long int plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:127:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  127 |   for (int i = 0; i < b.size(); i++)
      |                   ~~^~~~~~~~~~
railroad.cpp:128:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  128 |    for (int j = 0; j < b.size(); j++) {
      |                    ~~^~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 30 / 30
• Subtask 4: 0 / 36