Submission #1309303

#	Time	Username	Problem	Language	Result	Execution time	Memory
1309303		zzzzzzzzzzzzzzz	Stations (IOI20_stations)	C++20	100 / 100	397 ms	608 KiB

stations

/*#include <vector>

std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v);
int find_next_station(int s, int t, std::vector<int> c);


#include "stations.h"
#include <cstdio>
#include <cassert>
#include <map>
#include <vector>
#include <algorithm>

static int max_label = 0;
static int r, n, k, q;
static std::vector<int> u, v, labels, answers;
static std::map<int, int> reverse_labels;
static std::vector<std::vector<int>> adjlist;
static int s, t, w;
static std::vector<int> c;

int main() {
	assert(scanf("%d", &r) == 1);
	for (int tc = 0; tc < r; tc++) {
		assert(scanf("%d%d", &n, &k) == 2);
		u.resize(n - 1);
		v.resize(n - 1);
		adjlist.clear();
		adjlist.resize(n);
		for (int i = 0; i < n - 1; i++) {
			assert(scanf("%d%d", &u[i], &v[i]) == 2);
			adjlist[u[i]].push_back(v[i]);
			adjlist[v[i]].push_back(u[i]);
		}
		labels = label(n, k, u, v);
		if ((int)labels.size() != n) {
			printf("Number of labels not equal to %d\n", n);
			exit(0);
		}
		reverse_labels.clear();
		for (int i = 0; i < n; i++) {
			if (labels[i] < 0 || labels[i] > k) {
				printf("Label not in range 0 to %d\n", k);
				exit(0);
			}
			if (reverse_labels.find(labels[i]) != reverse_labels.end()) {
				printf("Labels not unique\n");
				exit(0);
			}
			reverse_labels[labels[i]] = i;
			if (labels[i] > max_label) {
				max_label = labels[i];
			}
		}
		assert(scanf("%d", &q) == 1);
		for (int i = 0; i < q; i++) {
			assert(scanf("%d%d%d", &s, &t, &w) == 3);
			c.clear();
			for (int v : adjlist[s]) {
				c.push_back(labels[v]);
			}
			std::sort(c.begin(), c.end());
			int answer = find_next_station(labels[s], labels[t], c);
			if (!std::binary_search(c.begin(), c.end(), answer)) {
				printf("Label %d returned by find_next_station not found in c\n", answer);
				exit(0);
			}
			answers.push_back(reverse_labels[answer]);
		}
	}
	printf("%d\n", max_label);
	for (int index : answers) {
		printf("%d\n", index);
	}
	exit(0);
}
*/

#include "stations.h"
#include <bits/stdc++.h>

using namespace std;

vector<vector<int>> g;
vector<int> lab,vis;

int ett(int node, int s, int p){
	vis[node]=1;
	if(p==0) lab[node]=s;
	for(int i:g[node]){
		if(vis[i]) continue;
		s=ett(i,s+1,p^1);
	}
	s++;
	if(p==1) lab[node]=s;
	return s;
}

vector<int> label(int n, int k, vector<int> u, vector<int> v) {
	g.clear();lab.clear();vis.clear();
	g.resize(n);lab.resize(n);vis.resize(n);
	map<int,int> key;
	for(int i=0;i<n-1;i++){
		g[u[i]].push_back(v[i]);
		g[v[i]].push_back(u[i]);
	}
	ett(0,0,0);
	for(int i=0;i<n;i++){
		key[lab[i]]=i;
	}
	sort(lab.begin(),lab.end());
	vector<int> ret(n);
	for(int i=0;i<n;i++){
		ret[key[lab[i]]]=i;
	}
	return ret;
}

int find_next_station(int s, int t, vector<int> c) {
	sort(c.begin(),c.end());
	int type=0;
	if(c[0]<s) type=1; 
	if(type==0){
		if(c.size()==1) return c[0];
		int st=s,en=c[c.size()-2]+1;
		if(st<=t && t<=en){
			for(int i=0;i<c.size()-1;i++) if(c[i]>=t) return c[i];
		} else{
			return c[c.size()-1];
		}
	} else{
		int st=c[0]+1,en=s;
		if(st<=t && t<=en){
			for(int i=c.size()-1;i>0;i--) if(c[i]<=t) return c[i];
		} else{
			return c[0];
		}
	}
}

Compilation message (stderr)

stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:139:1: warning: control reaches end of non-void function [-Wreturn-type]
  139 | }
      | ^

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