Submission #1104790

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104790		alexander707070	Simurgh (IOI17_simurgh)	C++14	70 / 100	179 ms	7248 KiB

simurgh

#include<bits/stdc++.h>

#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include "simurgh.h"

#define MAXN 507
#define MAXM 300007
using namespace std;
 
int n,m,dep[MAXN],edges;
vector< pair<int,int> > v[MAXN],tree[MAXN];

bool intree[MAXM],vis[MAXN];

pair<int,int> edge[MAXM],parent[MAXN];

int value[MAXM],st[MAXM],sumtree;
vector<int> ans;

unordered_set<int> s;

int questions;

int calc(vector<int> rem,vector<int> add){
	questions++;

	for(int i:rem)s.erase(i);
	for(int i:add)s.insert(i);

	vector<int> w;
	for(int i:s){
		w.push_back(i-1);
	}

	for(int i:rem)s.insert(i);
	for(int i:add)s.erase(i);

	return count_common_roads(w);
}

void dfs(int x){
	vis[x]=true;

	for(int i=0;i<v[x].size();i++){
		if(vis[v[x][i].first])continue;

		dep[v[x][i].first]=dep[x]+1;
		parent[v[x][i].first]={x,v[x][i].second};

		tree[x].push_back({v[x][i].first,v[x][i].second});
		tree[v[x][i].first].push_back({x,v[x][i].second});

		dfs(v[x][i].first);

		intree[v[x][i].second]=true;
		s.insert(v[x][i].second);
	}
}

vector<int> path,toask;
int total;

void dfs2(int x){
	vis[x]=true;

	for(int i=0;i<tree[x].size();i++){
		if(vis[tree[x][i].first])continue;

		toask.push_back(tree[x][i].second-1);
		total-=(value[tree[x][i].second]-1);

		dfs2(tree[x][i].first);
	}
}

bool ok;

void up(int x,int y){
	if(x==y)return;

	if(value[parent[x].second]==0 or ok){
		if(value[parent[x].second])ok=false;

		path.push_back(parent[x].second);
	}

	up(parent[x].first,y);
}

int howmany(int root,int l,int r){
	toask.clear();

	for(int i=1;i<=n;i++)vis[i]=false;

	vis[root]=true;
	for(int i=l;i<=r;i++)vis[v[root][i].first]=true;

	for(int i=l;i<=r;i++){
		toask.push_back(v[root][i].second-1);
	}

	total=0;

	dfs2(root);
	for(int i=l;i<=r;i++){
		dfs2(v[root][i].first);
	}

	questions++;
	total+=count_common_roads(toask);

	return total;
}

void solve(int root,int l,int r,int s){
	if(l==r){
		value[v[root][l].second]=2;
		return;
	}

	int mid=(l+r)/2;
	int lt=howmany(root,l,mid);

	if(lt>0){
		solve(root,l,mid,lt);
	}

	if(s-lt){
		solve(root,mid+1,r,s-lt);
	}
}
 
vector<int> find_roads(int N,vector<int> from,vector<int> to){

	n=N; m=int(from.size());

	double start=clock();

	for(int i=1;i<=m;i++){
		from[i-1]++; to[i-1]++;

		edge[i]={from[i-1],to[i-1]};

		v[from[i-1]].push_back({to[i-1],i});
		v[to[i-1]].push_back({from[i-1],i});
	}

	dfs(1);
	sumtree=calc({},{});

	for(int i=1;i<=m;i++){
		if(intree[i])continue;

		int u=from[i-1],w=to[i-1];
		if(dep[u]>dep[w])swap(u,w);

		path.clear(); ok=true;
		up(w,u);

		int mins=sumtree,maxs=sumtree,br=0,ask=0;

		for(int f:path){
			if(value[f]==0){
				st[f]=calc({f},{i});
				br++;

				mins=min(mins,st[f]);
				maxs=max(maxs,st[f]);
			}
		}

		if(br==0)continue;

		if(mins==maxs){
			for(int f:path){
				if(value[f]==0)continue;

				st[f]=calc({f},{i});
				ask=value[f];
				
				mins=min(mins,st[f]);
				maxs=max(maxs,st[f]);

				break;
			}
		}

		if(ask==0)ask=1;

		for(int f:path){
			if(value[f]!=0)continue;

			if(mins==maxs)value[f]=ask;
			else{
				if(st[f]==mins)value[f]=2;
				else value[f]=1;
			}
		}
	}

	if(questions>2*n)cout<<1/0;
	
	for(int i=1;i<=m;i++){
		if(intree[i] and value[i]==0)value[i]=2;
	}

	for(int i=1;i<=n;i++){
		solve(i,0,v[i].size()-1,howmany(i,0,v[i].size()-1));
	}

	for(int i=1;i<=m;i++){
		if(value[i]==2){
			ans.push_back(i-1);
		}
	}

	return ans;
}

Compilation message (stderr)

simurgh.cpp: In function 'void dfs(int)':
simurgh.cpp:46:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |  for(int i=0;i<v[x].size();i++){
      |              ~^~~~~~~~~~~~
simurgh.cpp: In function 'void dfs2(int)':
simurgh.cpp:68:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |  for(int i=0;i<tree[x].size();i++){
      |              ~^~~~~~~~~~~~~~~
simurgh.cpp: In function 'std::vector<int> find_roads(int, std::vector<int>, std::vector<int>)':
simurgh.cpp:203:26: warning: division by zero [-Wdiv-by-zero]
  203 |  if(questions>2*n)cout<<1/0;
      |                         ~^~
simurgh.cpp:139:9: warning: unused variable 'start' [-Wunused-variable]
  139 |  double start=clock();
      |         ^~~~~

• Subtask 1: 13 / 13
• Subtask 2: 17 / 17
• Subtask 3: 21 / 21
• Subtask 4: 19 / 19
• Subtask 5: 0 / 30