Submission #829309

#	Time	Username	Problem	Language	Result	Execution time	Memory
829309		vnm06	Highway Tolls (IOI18_highway)	C++14	51 / 100	110 ms	14608 KiB

highway

#include<bits/stdc++.h>
#include "highway.h"
using namespace std;

int n, m;
vector<int> u, v;
vector<int> gr[90009];

vector<int> sp;
vector<int> vpr;
int par[90009], pos[90009];
bool used[90009];

void dfs1(int v)
{
    used[v]=1;
    int brs=gr[v].size();
    for(int i=0; i<brs; i++)
    {
        int nv=gr[v][i];
        if(used[nv]) continue;
        par[nv]=v;
        dfs1(nv);
    }
    sp.push_back(v);
}

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B)
{
    n=N;
    u=U;
    v=V;
    int m = U.size();
    for(int i=0; i<m; i++)
    {
        gr[u[i]].push_back(v[i]);
        gr[v[i]].push_back(u[i]);
    }
    dfs1(0);
    vpr.resize(m);
    for(int i=0; i<m; i++) vpr[i]=0;
    ///cout<<1<<endl;
    long long expcost=ask(vpr);
    for(int i=0; i<m; i++)
    {
        if(par[u[i]]==v[i]) pos[u[i]]=i;
        else if(par[v[i]]==u[i]) pos[v[i]]=i;
    }
    int le=0, ri=n-2;
    ///cout<<1<<endl;
    while(le<ri)
    {
        int mid=(le+ri)/2;
        for(int i=0; i<m; i++) vpr[i]=0;
        for(int j=le; j<=mid; j++) vpr[pos[sp[j]]]=1;
        if(ask(vpr)!=expcost) ri=mid;
        else le=mid+1;
    }
    ///cout<<sp[le]<<endl;
    int v1=sp[le];
    sp.resize(0);
    for(int i=0; i<n; i++) par[i]=pos[i]=used[i]=0;
    vpr.resize(0);



    dfs1(v1);
    vpr.resize(m);
    for(int i=0; i<m; i++) vpr[i]=0;
    ///cout<<1<<endl;
    expcost=ask(vpr);
    for(int i=0; i<m; i++)
    {
        if(par[u[i]]==v[i]) pos[u[i]]=i;
        else if(par[v[i]]==u[i]) pos[v[i]]=i;
    }
    le=0, ri=n-2;
    while(le<ri)
    {
        int mid=(le+ri)/2;
        for(int i=0; i<m; i++) vpr[i]=0;
        for(int j=le; j<=mid; j++) vpr[pos[sp[j]]]=1;
        if(ask(vpr)!=expcost) ri=mid;
        else le=mid+1;
    }
    answer(v1, sp[le]);
}

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