Submission #490546

#	Time	Username	Problem	Language	Result	Execution time	Memory
490546		mraron	Stations (IOI20_stations)	C++14	100 / 100	876 ms	736 KiB

stations

#include "stations.h"
#include <vector>
#include <cmath>
#include <iostream>
#include <algorithm>
using namespace std;

vector<vector<int>> adj;
vector<int> L, R, lvl;
int ind;
void dfs(int x) {
	L[x]=ind++;
	for(auto i:adj[x]) {
		if(!L[i]) {
			lvl[i]=lvl[x]+1;
			dfs(i);
		}
	}
	R[x]=ind++;
}

std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v) {
	adj.resize(n);
	for(auto& i:adj) i.clear();
	
	for(int i=0;i<n-1;++i) {
		adj[u[i]].push_back(v[i]);
		adj[v[i]].push_back(u[i]);
		//~ cerr<<u[i]<<" "<<v[i]<<"\n";
	}
	
	L.assign(n, 0);
	R.assign(n, 0);
	lvl.assign(n, 0);
	ind=1;
	dfs(0);
	
	std::vector<int> labels(n);
	for (int i = 0; i < n; i++) {
		labels[i] = lvl[i]&1?L[i]:R[i];
		//~ std::cerr<<i<<"("<<lvl[i]<<")"<<" ";
	}
	//~ cerr<<"\n";
	
	vector<int> s(labels.begin(), labels.end());
	sort(s.begin(), s.end());
	for(int i=0;i<n;++i) labels[i]=lower_bound(s.begin(), s.end(), labels[i])-s.begin();
	
	//~ for(auto i:labels) cerr<<i<<" ";cerr<<"\n";
	
	return labels;
}

bool contains(int a, int b, int x) {
	return min(a, b)<=x && x<=max(a, b);
}


int find_next_station(int s, int t, std::vector<int> c) {
	int best=-1;
	for(int i:c) {
		if(contains(s, i, t)) {
			if(best==-1 || abs(best-s)>abs(s-i)) best=i;
		}
	}
	
	if(best==-1) {
		for(int i:c) {
			if(best==-1 || abs(best-s)<abs(s-i)) best=i;
		}
	}
	
	return best;
}

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 16 / 16
• Subtask 4: 10 / 10
• Subtask 5: 61 / 61