Submission #302345

#	Time	Username	Problem	Language	Result	Execution time	Memory
302345		JPN20	Roller Coaster Railroad (IOI16_railroad)	C++17	34 / 100	242 ms	55008 KiB

railroad

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

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

// Graph
bool used[1 << 18];
int cnt[1 << 18];
int col[1 << 18], cntv;
vector<int> ord;
vector<int> X[1 << 18];
vector<int> Y[1 << 18];

void dfs1(int pos) {
	used[pos] = true;
	for (int i : X[pos]) {
		if (used[i] == true) continue;
		dfs1(i);
	}
	ord.push_back(pos);
}

void dfs2(int pos) {
	col[pos] = cntv;
	for (int i : Y[pos]) {
		if (col[i] >= 1) continue;
		dfs2(i);
	}
}

long long solve_subtask3() {
	// ZAATS
	vector<long long> vec;
	vec.push_back(0);
	vec.push_back(1000000007);
	for (int i = 0; i < N; i++) vec.push_back(S[i]);
	for (int i = 0; i < N; i++) vec.push_back(T[i]);
	sort(vec.begin(), vec.end());
	vec.erase(unique(vec.begin(), vec.end()), vec.end());
	for (int i = 0; i < N; i++) S[i] = lower_bound(vec.begin(), vec.end(), S[i]) - vec.begin();
	for (int i = 0; i < N; i++) T[i] = lower_bound(vec.begin(), vec.end(), T[i]) - vec.begin();
	
	// GRAPH
	cnt[0] += 1;
	cnt[vec.size() - 1] -= 1;
	X[vec.size() - 1].push_back(0);
	Y[0].push_back(vec.size() - 1);
	for (int i = 0; i < N; i++) X[S[i]].push_back(T[i]);
	for (int i = 0; i < N; i++) Y[T[i]].push_back(S[i]);
	for (int i = 0; i < N; i++) cnt[S[i]] -= 1;
	for (int i = 0; i < N; i++) cnt[T[i]] += 1;
	
	// HANTE
	for (int i = 1; i < (int)vec.size(); i++) cnt[i] += cnt[i - 1];
	for (int i = 0; i < (int)vec.size(); i++) {
		if (cnt[i] <= -1) return 1000000007;
		if (cnt[i] >= 1) { X[i].push_back(i + 1); Y[i + 1].push_back(i); }
	}
	
	// SCC
	for (int i = 0; i < (int)vec.size(); i++) {
		if (used[i] == true) continue;
		dfs1(i);
	}
	for (int i = ord.size() - 1; i >= 0; i--) {
		if (col[ord[i]] >= 1) continue;
		cntv++;
		dfs2(ord[i]);
	}
	
	// FINAL
	if (cntv == 1) return 0;
	return 1000000007;
}

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;
}

int cnts = 0;

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];
	cnts += 1;
	
	if (N <= 16) return solve_subtask2();
	return solve_subtask3();
}

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