Submission #1021380

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021380		mansur	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	151 ms	18224 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
 
using namespace std;

#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(s) (int)s.size()
#define s second
#define f first

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
 
const int N = 1e6, inf = 1e9 + 5;

int pr[N], sz[N];

int get(int x) {
	if (pr[x] == x) return x;
	return pr[x] = get(pr[x]);
}

void unite(int a, int b) {
	a = get(a);
	b = get(b);
	if (a == b) return;
	if (sz[a] > sz[b]) swap(a, b);
	pr[a] = b, sz[b] += sz[a];
}
                                                                                                                      
ll plan_roller_coaster(vector<int> s, vector<int> t) {
	vector<int> x;
	t.push_back(1);
	s.push_back(inf);
	for (int v: s) x.push_back(v);
	for (int v: t) x.push_back(v);
	sort(all(x));
	x.erase(unique(all(x)), x.end());
	int n = sz(s), m = sz(x);
	vector<int> cnt(m);
	for (int i = 0; i < m; i++) pr[i] = i, sz[i] = 1;
	for (int i = 0; i < n; i++) {
		s[i] = lower_bound(all(x), s[i]) - x.begin();
		t[i] = lower_bound(all(x), t[i]) - x.begin();
		unite(s[i], t[i]);
		if (s[i] <= t[i]) cnt[s[i]]++, cnt[t[i]]--;
		else cnt[t[i]]--, cnt[s[i]]++;
	}                                                  
	ll ans = 0;
	vector<array<int, 3>> g;
	for (int i = 0; i < m; i++) {
		if (i) cnt[i] += cnt[i - 1];
		if (cnt[i]) unite(i, i + 1);
		else g.push_back({x[i + 1] - x[i], i, i + 1});
		if (cnt[i] > 0) ans += (x[i + 1] - x[i]) * 1ll * cnt[i];		
	}
	sort(all(g));
	for (auto [w, a, b]: g) {
		a = get(a), b = get(b);
		if (a == b) continue;
		ans += w;
		unite(a, b);
	}
	return ans;
}

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