Submission #687332

#	Time	Username	Problem	Language	Result	Execution time	Memory
687332		alexdd	Easter Eggs (info1cup17_eastereggs)	C++17	71.60 / 100	55 ms	1080 KiB

eastereggs

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

using namespace std;
int n;
vector<int> con[520];
vector<int> children[520];
vector<int> forniv[520];
int level[520];
bool visited[520];
int parent[520];
int rez=-1;
int mxmniv=0;
int root;
int cntq;
void dfs(int nod)
{
    visited[nod]=1;
    mxmniv = max(mxmniv, level[nod]);
    forniv[level[nod]].push_back(nod);
    for(auto adj:con[nod])
    {
        if(!visited[adj])
        {
            level[adj] = level[nod]+1;
            parent[adj]=nod;
            dfs(adj);
            for(int i=0;i<children[adj].size();i++)
                children[nod].push_back(children[adj][i]);
        }
    }
    children[nod].push_back(nod);
}
vector<int> aux;
void dfs2(int nod, int niv)
{
    visited[nod]=1;
    aux.push_back(nod);
    for(auto adj:con[nod])
    {
        if(!visited[adj] && level[adj]<=niv)
        {
            dfs2(adj, niv);
        }
    }
}

bool verif_nivel(int niv)
{
    for(int i=1;i<=n;i++)
        visited[i]=0;
    aux.clear();
    dfs2(root,niv);
    cntq--;
    return query(aux);
}

int find_nivel()
{
    int st,dr,mij;
    st=1;
    dr=mxmniv;
    while(st<=dr)
    {
        if(st==dr)
            return st;
        mij=(st+dr)/2;
        if(verif_nivel(mij))
            dr=mij;
        else
            st=mij+1;
    }
    return mij;
}

int fr[520];
bool verif_interval(int le, int ri, int niv)///returneaza 1 daca oul se afla in nodurile de pe forniv[niv][le..ri]
{
    aux.clear();
    for(int i=1;i<=n;i++)
        fr[i]=0;
    for(int i=le;i<=ri;i++)
    {
        int cur=forniv[niv][i];
        while(cur!=-1)
        {
            fr[cur]++;
            cur = parent[cur];
        }
    }
    for(int i=1;i<=n;i++)
    {
        if(fr[i]>0)
            aux.push_back(i);
    }
    cntq--;
    return query(aux);
}

int findEgg (int N, vector < pair < int, int > > bridges)
{
    n=N;
    if(n<=16)
        cntq = 4;
    else if(n<=500)
        cntq = 9;
    else
        cntq = 9;
    for(int i=1;i<=N;i++)
    {
        visited[i]=0;
        con[i].clear();
        children[i].clear();
        forniv[i].clear();
    }
    rez=-1;
    mxmniv=0;
    for(auto x:bridges)
    {
        con[x.first].push_back(x.second);
        con[x.second].push_back(x.first);
    }
    root=1;
    level[root] = 1;
    parent[root] = -1;
    dfs(root);

    int niv = find_nivel();

    int st,dr,mij=0;
    st=0;
    dr=forniv[niv].size()-1;
    while(st<=dr)
    {
        if(st==dr)
            return forniv[niv][st];
        if(dr-st+1<=cntq)
        {
            for(int i=st;i<=dr;i++)
            {
                if(query({forniv[niv][i]}))
                    return forniv[niv][i];
            }
        }
        mij=(st+dr)/2;
        if(verif_interval(st,mij,niv))
            dr=mij;
        else
            st=mij+1;
    }
    return forniv[niv][mij];
}

Compilation message (stderr)

eastereggs.cpp: In function 'void dfs(int)':
eastereggs.cpp:28:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |             for(int i=0;i<children[adj].size();i++)
      |                         ~^~~~~~~~~~~~~~~~~~~~~
eastereggs.cpp: In function 'int find_nivel()':
eastereggs.cpp:60:15: warning: 'mij' may be used uninitialized in this function [-Wmaybe-uninitialized]
   60 |     int st,dr,mij;
      |               ^~~

• Subtask 1: 32 / 40
• Subtask 2: 26.4 / 40
• Subtask 3: 13.2 / 20