Submission #913882

#	Time	Username	Problem	Language	Result	Execution time	Memory
913882		Asymmetry	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	1934 ms	126384 KiB

railroad

#include<bits/stdc++.h>
using namespace std;
using LL=long long;
#define FOR(i,l,r)for(int i=(l);i<=(r);++i)
#define REP(i,n)FOR(i,0,(n)-1)
#define ssize(x)int(x.size())
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

LL plan_roller_coaster(vector<int> s, vector<int> t) {
	int n = ssize(s);
	map<int, int> imp;
	vector<pair<int, int>> edges;
	REP (i, n) {
		++imp[s[i]];
		--imp[t[i]];
		edges.emplace_back(s[i], t[i]);
		debug(s[i], t[i]);
	}
	const int INF = 1e9;
	--imp[1];
	++imp[INF];
	edges.emplace_back(INF, 1);
	debug(imp);
	vector<pair<int, int>> stc;
	int sum = 0;
	LL answer = 0;
	for (auto [speed, delta] : imp) {
		debug(speed, delta, sum, stc);
		if (sum > 0 && delta < 0) {
			while (ssize(stc) && delta) {
				auto [beg, cnt] = stc.back();
				stc.pop_back();
				edges.emplace_back(speed, beg);
				answer += speed - beg;
				--cnt;
				++delta;
				--sum;
				if (cnt)
					stc.emplace_back(beg, cnt);
			}
		}
		else if (sum < 0 && delta > 0) {
			while (ssize(stc) && delta) {
				auto [beg, cnt] = stc.back();
				stc.pop_back();
				edges.emplace_back(beg, speed);
				--cnt;
				--delta;
				++sum;
				if (cnt)
					stc.emplace_back(beg, cnt);
			}
		}
		debug("again", speed, delta, sum, stc);
		if (delta) {
			stc.emplace_back(speed, abs(delta));
			sum += delta;
		}
		else if (ssize(stc) && stc.back().first != speed) {
			debug("special");
			auto [beg, cnt] = stc.back();
			stc.pop_back();
			if (sum > 0) {
				edges.emplace_back(speed, beg);
				answer += speed - beg;
			}
			else {
				edges.emplace_back(beg, speed);
			}
			--cnt;
			if (cnt)
				stc.emplace_back(beg, cnt);
			stc.emplace_back(speed, 1);
		}
	}
	assert(sum == 0);
	debug(edges);
	debug(answer);
	map<int, int> color;
	map<int, vector<int>> graph;
	for (auto [u, v] : edges)
		graph[u].emplace_back(v);
	int m = 0;
	for (const auto &[i, adj] : graph) {
		if (!color.count(i)) {
			function<void(int)> dfs = [&](int v) {
				color[v] = m;
				for (int u : graph[v])
					if (!color.count(u))
						dfs(u);
			};
			dfs(i);
			++m;
		}
	}
	debug(color);
	vector<int> rep(m);
	iota(rep.begin(), rep.end(), 0);
	function<int(int)> fin = [&](int v) {
		if (v != rep[v])
			rep[v] = fin(rep[v]);
		return rep[v];
	};
	auto uni = [&](int a, int b) {
		a = fin(a);
		b = fin(b);
		if (a == b)
			return false;
		rep[b] = a;
		return true;
	};
	int last = 1;
	vector<tuple<int, int, int>> sr;
	for (auto [pos, type] : color) {
		if (color[last] != type) {
			sr.emplace_back(pos - last, color[last], type);
		}
		last = pos;
	}
	sort(sr.begin(), sr.end());
	for (auto [cost, a, b] : sr) {
		debug(cost, a, b);
		if (uni(a, b))
			answer += cost;
	}
	return answer;
}

#ifdef LOCAL
int main() {
	cin.tie(0)->sync_with_stdio(0);
	int n;
	cin >> n;
	vector<int> s(n), t(n);
	REP (i, n)
		cin >> s[i] >> t[i];
	cout << plan_roller_coaster(s, t) << endl;
}
#endif

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