Submission #302162

#	Time	Username	Problem	Language	Result	Execution time	Memory
302162		JPN20	Roller Coaster Railroad (IOI16_railroad)	C++17	34 / 100	265 ms	17436 KiB

railroad

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

long long N;
long long S[1 << 18], T[1 << 18];
long long dp[1 << 16][16];

bool calc(int stt, int goa) {
	vector<int> vec;
	for (int i = 0; i < N; i++) {
		if (i == stt) continue;
		int pos1 = lower_bound(T, T + N, S[i] + 1) - T;
		if (goa < pos1) pos1--;
		vec.push_back(pos1);
	}
	sort(vec.begin(), vec.end());
	for (int i = 0; i < vec.size(); i++) {
		if (vec[i] <= i) return false;
	}
	return true;
}

long long solve_subtask3() {
	// SORTS
	vector<pair<long long, long long>> vec;
	for (int i = 0; i < N; i++) vec.push_back(make_pair(T[i], S[i]));
	sort(vec.begin(), vec.end());
	for (int i = 0; i < N; i++) T[i] = vec[i].first;
	for (int i = 0; i < N; i++) S[i] = vec[i].second;
	
	// PRCLC
	vector<pair<int, int>> vecs;
	for (int i = 0; i < N; i++) vecs.push_back(make_pair(S[i], i));
	sort(vecs.begin(), vecs.end());
	
	// FINAL
	int u1 = vecs[0].second, u2 = vecs[1].second;
	int v1 = 0, v2 = 1;
	bool flag = false;
	if (u1 != v1 && calc(u1, v1) == true) flag = true;
	if (u1 != v2 && calc(u1, v2) == true) flag = true;
	if (u2 != v1 && calc(u2, v1) == true) flag = true;
	if (flag == true) return 0;
	return 1000000007LL;
}

long long solve_subtask2() {
	// PRCLC
	for (int i = 0; i < (1 << N); i++) {
		for (int j = 0; j < N; j++) dp[i][j] = (1LL << 60);
	}
	for (int i = 0; i < N; i++) dp[1 << i][i] = 0;
	
	// CALC
	for (int i = 0; i < (1 << N); i++) {
		for (int j = 0; j < N; j++) {
			if (dp[i][j] == (1LL << 60)) continue;
			for (int k = 0; k < N; k++) {
				if ((i / (1 << k)) % 2 == 1) continue;
				long long cost = max(0LL, T[j] - S[k]);
				dp[i + (1 << k)][k] = min(dp[i + (1 << k)][k], dp[i][j] + cost);
			}
		}
	}
	
	// FINAL
	long long Answer = (1LL << 60);
	for (int i = 0; i < N; i++) Answer = min(Answer, dp[(1 << N) - 1][i]);
	return Answer;
}

long long plan_roller_coaster(vector<int> s, vector<int> t) {
	N = s.size();
	for (int i = 0; i < N; i++) S[i] = s[i];
	for (int i = 0; i < N; i++) T[i] = t[i];
	
	if (N <= 16) return solve_subtask2();
	return solve_subtask3();
}

Compilation message (stderr)

railroad.cpp: In function 'bool calc(int, int)':
railroad.cpp:18:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |  for (int i = 0; i < vec.size(); i++) {
      |                  ~~^~~~~~~~~~~~

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