Submission #434109

#	Time	Username	Problem	Language	Result	Execution time	Memory
434109		kwongweng	Stations (IOI20_stations)	C++17	100 / 100	1186 ms	940 KiB

stations

#include <bits/stdc++.h>
#include "stations.h"
using namespace std;
typedef vector<int> vi;
#define pb push_back

vi g[2000];
vi ans, sz, used;
int cur;

void dfs1(int u = 0, int p = -1, int d = 0){
	for (int v : g[u]){
		if (v == p) continue;
		dfs1(v, u, d+1);
		sz[u] += sz[v] + 1;
	}
}

void dfs2(int u = 0, int p = -1, int d = 0){
	if (d % 2 == 0){
		used[cur] = 1;
		ans[u] = cur;
		while (used[cur]) cur++;
	}else{
		used[cur+sz[u]] = 1;
		ans[u] = cur+sz[u];
		while (used[cur]) cur++;
	}
	for (int v : g[u]){
		if (v == p) continue;
		dfs2(v, u, d+1);
	}
}

vi label(int n, int k, vi u, vi v) {
	cur = 0;
	vi answer; answer.resize(n, 0);
	ans.resize(n, 0); sz.resize(n, 0); used.resize(n, 0);
	for (int i = 0; i < n-1; i++){
		g[u[i]].pb(v[i]);
		g[v[i]].pb(u[i]);
	}
	dfs1();
	dfs2();
	answer = ans;
	ans.clear(); sz.clear(); used.clear();
	for (int i = 0; i < n; i++) g[i].clear();
	return answer;
}

int find_next_station(int s, int t, vi c) {
	int C = c.size();
	if (C==1) return c[0];
	if (s < c[0]){
		if (t < s || t >= c[C-1]) return c[C-1];
		int ans = s;
		for (int i = 0; i < C-1; i++){
			if (ans < t && t <= c[i]) return c[i];
			ans = c[i];
		}
		return c[C-1];
	}
	if (t > s || t <= c[0]) return c[0];
	int ans = s;
	for (int i = C-1; i > 0; i--){
		if (ans > t && t >= c[i]) return c[i];
		ans = c[i];
	}
	return c[0];
}

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