Submission #293999

#	Time	Username	Problem	Language	Result	Execution time	Memory
293999		Dovran	Highway Tolls (IOI18_highway)	C++11	0 / 100	3068 ms	16044 KiB

highway

#include <bits/stdc++.h>
#include "highway.h"
#define N 200009
#define pii pair <int, int>
#define ff first
#define ss second
#define sz size
#define pb push_back
#define ll long long

using namespace std;

int n, m, ln;
vector<int>e[N];
vector<int>asd;
map<int, int>c[N];
int ansS, ansT;

void find_pair(int NN, std::vector<int>u, std::vector<int>v, int a, int b){
	n=NN;
	m=u.size();
	for(int i=0; i<m; i++){
		e[u[i]].pb(v[i]);
		e[v[i]].pb(u[i]);
		
		c[v[i]][u[i]]=i;
		c[u[i]][v[i]]=i;
		
		
		asd.pb(0);
	}
	ln=ask(asd);
	int l=0, r=m-1;
	int x, in;
	while(r>=l){
		int md=(l+r)/2;
		for(int i = 0; i < m; i++) asd[i] = 0;
		for(int i=0; i<=md; i++) asd[i]=1;
		
		x=ask(asd);
		
		if(x==ln) l=md+1;
		else in = md, r=md-1;
	}
//	answer(0, 0);
//	return;
	queue<int> q;
	queue<int> q2;
	q.push(u[in]);
	q2.push(v[in]);
	int vis[N];
	vis[u[in]]=1, vis[v[in]]=1;
	
	vector<int> p, p2;
	int lft=0, rgt=0;
	while(!q.empty() and !q2.empty()){
		if(!lft){
			p.clear();
			int nd=q.front();
			q.pop();
			for(auto i:e[nd])
				if(!vis[i])
					vis[i]=vis[nd]+1, p.pb(i), q.push(i);
			
			sort(p.begin(), p.end());
			
			for(int i=0; i<m; i++)
				asd[i]=0;
			for(auto i:p)
				for(auto j:e[i]) asd[c[i][j]]=1;
			
			x=ask(asd);
			if(x!=ln){
				l=0, r=p.sz()-1;
				while(l>=r){
					int md=(l+r)/2;
					for(int i=0; i<m; i++)
						asd[i]=0;
					for(int i=0; i<=md; i++)
						for(auto j:e[p[i]]) asd[c[p[i]][j]]=1;
					x=ask(asd);
					if(x!=ln)
						in=md, r=md-1;
					else l=md+1;
					
				}
				ansS=p[in];
				lft=1;
			}
		}
		if(!rgt){
			p2.clear();
			int nd2=q2.front();
			q2.pop();
			for(auto i:e[nd2])
				if(!vis[i])
					vis[i]=vis[nd2]+1, p2.pb(i), q2.push(i);
			sort(p2.begin(), p2.end());
			
			for(int i=0; i<m; i++)
				asd[i]=0;
			for(auto i:p2)
				for(auto j:e[i]) asd[c[i][j]]=1;
			
			x=ask(asd);
			if(ask(asd)!=ln){
				l=0, r=p2.sz()-1;
				while(l>=r){
					int md=(l+r)/2;
					for(int i=0; i<m; i++)
						asd[i]=0;
					for(int i=0; i<=md; i++)
						for(auto j:e[p2[i]]) asd[c[p2[i]][j]]=1;
					x=ask(asd);
					if(x!=ln)
						in=md, r=md-1;
					else l=md+1;
					
				}
				ansT=p2[in];
				rgt=1;
			}
		}
	}
	answer(ansS, ansT);
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:49:13: warning: 'in' may be used uninitialized in this function [-Wmaybe-uninitialized]
   49 |  q.push(u[in]);
      |             ^

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 6
• Subtask 4: 0 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31