Submission #617145

#	Time	Username	Problem	Language	Result	Execution time	Memory
617145		maximath_1	Roller Coaster Railroad (IOI16_railroad)	C++11	100 / 100	173 ms	21084 KiB

railroad

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

#define ll long long
const int MX = 2e5 + 5;
const int inf = 1e9 + 69;

int par[MX];
int find(int nw){
	return par[nw] = (par[nw] == nw ? nw : find(par[nw]));
}
bool uni(int u, int v){
	u = find(u); v = find(v);
	par[u] = v; return (u != v);
}

ll plan_roller_coaster(vector<int> s, vector<int> t){
	int n = (int)s.size();
	for(int i = 0; i < MX; i ++) par[i] = i;

	vector<pair<int, pair<int, int> > > li, edges;
	for(int i = 0; i < n; i ++){ // edge si -> ti
		li.push_back({s[i], {1, i}});
		li.push_back({t[i], {-1, i}});
	} // edge inf -> 1
	li.push_back({inf, {1, n}});
	li.push_back({1, {-1, n}});

	sort(li.begin(), li.end());

	int balance = 0;
	ll ans = 0ll;
	for(int i = 0; i + 1 < li.size(); i ++){
		balance += li[i].second.first;
		ans += max(0, balance) * 1ll * (li[i + 1].first - li[i].first);
		edges.push_back({li[i + 1].first - li[i].first, {li[i + 1].second.second, li[i].second.second}});
		if(li[i + 1].first == li[i].first || balance != 0)
			uni(li[i + 1].second.second, li[i].second.second);
	}

	sort(edges.begin(), edges.end());
	for(auto i : edges) if(uni(i.second.first, i.second.second)) ans += i.first;

	return ans;
}

Compilation message (stderr)

railroad.cpp: In function 'long long int plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:34:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, std::pair<int, int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |  for(int i = 0; i + 1 < li.size(); i ++){
      |                 ~~~~~~^~~~~~~~~~~

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