Submission #1063214

#	Time	Username	Problem	Language	Result	Execution time	Memory
1063214		nightfal	Stations (IOI20_stations)	C++17	100 / 100	634 ms	1204 KiB

stations

#include <vector>
#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;

template <typename T> void print(T elem) {cout << elem << " ";}
template <typename T> void print(vector<T> &v) {for(auto elem: v) print(elem); cout << endl;}
template <typename T> void print(vector<vector<T>> &v) {for(auto elem: v) print(elem); cout << endl;}

void makeG(vector<vector<int>> &g, vector<int> &u, vector<int> &v) {
	for(int i=0; i<u.size(); i++) {
		g[u[i]].push_back(v[i]);
		g[v[i]].push_back(u[i]);
	}
}
int labelSubDecision(int n, int k, vector<vector<int>> &g, vector<int> &u, vector<int> &v) {
	return 5;
	if (k==pow(10,9)) return 5;
	int cnt = 0;
	for(int i=0; i<n; i++) if (g[i].size()>2) cnt++;
	if (cnt==0) return 1;

	bool subtask2 = true;
	for(int i=0; i<u.size(); i++)
		if (!(u[i]==i+1 && v[i]==i/2 || u[i]==i/2 && v[i]==i+1)) subtask2= false;
	if (subtask2) return 2;
	if (cnt==1) return 3;
}
void labelLine(int cnt, int node, vector<vector<int>> &g, vector<int> &labels) {
	while(labels[node]==-1) {
		labels[node] = cnt++;
		for(int elem: g[node]) if (labels[elem]==-1) node = elem;
	}
}
void label1(int n, vector<vector<int>> &g, vector<int> &labels) {
	int node = 0;
	for(int i=0; i<n; i++) if(g[i].size()==1) {node=i; break;}
	labelLine(0,node,g,labels);
}
void label2(int n, vector<int> &labels) {
	for(int i=0; i<n; i++) labels[i] = i+1;
}
void label3(int n, vector<vector<int>> &g, vector<int> &labels) {
	int root = 0;
	for(int i=0; i<n; i++) if(g[i].size() > 2) {root = i; break;}
	labels[root] = 1'000;
	for(int i=0; i<g[root].size(); i++) {
		int child = g[root][i];
		labelLine((i+1)*1'000+1,child,g,labels);
	}
}
void dfs(int node, int offset, vector<vector<int>> &g, vector<int> &labels) {
	for(int i=0; i<g[node].size(); i++) {
		int child = g[node][i];
		if(labels[child]!=-1) continue;
		labels[child] = labels[node] + offset*(i+1);
		dfs(child,offset/10,g,labels);
	}
}
void label4(vector<vector<int>> &g, vector<int> &labels) {
	labels[0] = pow(10,7);
	dfs(0,pow(10,6),g,labels);
}
int dfs2(int node, int cnt, int d, vector<vector<int>> &g, vector<int> &pre, vector<int> &post, vector<int> &dist) {
	if (pre[node]!=-1) return cnt;
	pre[node] = cnt++;
	dist[node] = d++;
	for(int child: g[node])
		cnt = dfs2(child,cnt,d,g,pre,post,dist);
	post[node] = cnt++;
	return cnt;
}
void relabel(int n, vector<int> &labels) {
	vector<pair<int,int>> temp;
	for(int i=0; i<n; i++)
		temp.push_back({labels[i],i});
	sort(temp.begin(),temp.end());
	for(int i=0; i<n; i++)
		labels[temp[i].second] = i;
}
void label5(int n, vector<vector<int>> &g, vector<int> &labels) {
	vector<int> pre(n,-1), post(n,-1), dist(n,-1);
	dfs2(0,0,0,g,pre,post,dist);
	for(int i=0; i<n; i++)
		labels[i] = dist[i]%2? post[i]:pre[i];
	relabel(n, labels);
}
std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v) {
	vector<vector<int>> g(n);
	makeG(g,u,v);
	int subtask = labelSubDecision(n,k,g,u,v);
	vector<int> labels(n,-1);
	switch(subtask) {
		case 1: label1(n,g,labels); return labels;
		case 2: label2(n,labels); return labels;
		case 3: label3(n,g,labels); return labels;
		case 4: label4(g,labels); return labels;
		case 5: label5(n,g,labels); return labels;
	}
}
int findSubDecision(int s, int t, vector<int> &c) {
	return 5;
	// if (s >= pow(10,7)) return 4;
	// if (s >= 1'000 && t >= 1'000) return 3;
	for(int i=0; i<c.size(); i++)
		if (c[i] < s-1 || c[i] > s+1) return 2;
	return 1;
}
int find1(int s, int t, vector<int> &c) {
	if (c.size()==1) return c[0];
	else return t<s? c[0]:c[1];
}
bool ancestor(int a, int b) {
	if (a==0) return true;
	while(b!=0) { if(a==b) return true; else b >>= 1; }
	return false;
}
int find2(int s, int t, vector<int> &c) {
	reverse(c.begin(),c.end());
	for(int elem: c) if(ancestor(elem,t)) return elem;
	return c[c.size()-1];
}
int find3(int s, int t, vector<int> &c) {
	if (s==1'000) { for(int elem: c) if(t/1000==elem/1000) return elem; }
	else if (s/1000 == t/1000 && s < t) { for(int elem: c) if(elem > s) return elem; }
	else { for(int elem: c) if(elem < s) return elem; }
}
bool ancestor4(int a, int b) {
	int divisor = 1;
	for(int i=0; i<=7; i++) {
		if (b - b % divisor == a) return true;
		divisor *= 10;
	}
	return false;
}
int find4(int s, int t, vector<int> &c) {
	reverse(c.begin(),c.end());
	for(int elem: c) if(ancestor4(elem,t)) return elem;
	return c[c.size()-1];
}
int find5(int s, int t, vector<int> &c) {
	int m = c.size();
	if (m==1) return c[0];
	else if (s==0) { for(int elem: c) if(t<=elem) return elem; }
	else if (s<c[0]) { // s is pre and c[i] is post.
		if (t<s) return c[m-1];
		for(int i=0; i<m-1; i++) if (t<=c[i]) return c[i];
		return c[m-1];
	}
	else { // s is post and c[i] is pre.
		if (t>s) return c[0];
		for(int i=1; i<m; i++) 
			if(t < c[i]) return c[i-1];
		return c[m-1];
	}
}
int find_next_station(int s, int t, std::vector<int> c) {
	int subtask = findSubDecision(s,t,c);
	switch(subtask) {
		case 1: return find1(s,t,c);
		case 2: return find2(s,t,c);
		case 3: return find3(s,t,c);
		case 4: return find4(s,t,c);
		case 5: return find5(s,t,c);
	}
	return c[0];
}

Compilation message (stderr)

stations.cpp: In function 'void makeG(std::vector<std::vector<int> >&, std::vector<int>&, std::vector<int>&)':
stations.cpp:12:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |  for(int i=0; i<u.size(); i++) {
      |               ~^~~~~~~~~
stations.cpp: In function 'int labelSubDecision(int, int, std::vector<std::vector<int> >&, std::vector<int>&, std::vector<int>&)':
stations.cpp:25:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |  for(int i=0; i<u.size(); i++)
      |               ~^~~~~~~~~
stations.cpp:26:19: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   26 |   if (!(u[i]==i+1 && v[i]==i/2 || u[i]==i/2 && v[i]==i+1)) subtask2= false;
stations.cpp: In function 'void label3(int, std::vector<std::vector<int> >&, std::vector<int>&)':
stations.cpp:48:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |  for(int i=0; i<g[root].size(); i++) {
      |               ~^~~~~~~~~~~~~~~
stations.cpp: In function 'void dfs(int, int, std::vector<std::vector<int> >&, std::vector<int>&)':
stations.cpp:54:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for(int i=0; i<g[node].size(); i++) {
      |               ~^~~~~~~~~~~~~~~
stations.cpp: In function 'int findSubDecision(int, int, std::vector<int>&)':
stations.cpp:106:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |  for(int i=0; i<c.size(); i++)
      |               ~^~~~~~~~~
stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:90:25: warning: control reaches end of non-void function [-Wreturn-type]
   90 |  vector<vector<int>> g(n);
      |                         ^
stations.cpp: In function 'int find3(int, int, std::vector<int>&)':
stations.cpp:128:1: warning: control reaches end of non-void function [-Wreturn-type]
  128 | }
      | ^
stations.cpp: In function 'int find5(int, int, std::vector<int>&)':
stations.cpp:157:1: warning: control reaches end of non-void function [-Wreturn-type]
  157 | }
      | ^

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