Submission #1005891

#	Time	Username	Problem	Language	Result	Execution time	Memory
1005891		irmuun	Highway Tolls (IOI18_highway)	C++17	51 / 100	216 ms	262144 KiB

highway

#include<bits/stdc++.h>
#include "highway.h"
 
using namespace std;
 
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()

const int maxn=9e4+5;

int n,m,a,b;
vector<int>u,v;

vector<pair<int,int>>adj[maxn];
vector<int>dep(maxn,0),edge(maxn,0),w,L,R,edges;
int cur=0;

void dfs(int x,int p){
    if(cur==0) L.pb(x);
    else R.pb(x);
    for(auto [y,e]:adj[x]){
        if(y!=p){
            if(cur==0){
                edges.pb(e);
            }
            dep[y]=dep[x]+1;
            edge[y]=e;
            dfs(y,x);
        }
    }
}

void find_pair(int N,vector<int>U,vector<int>V,int A, int B){
    n=N,u=U,v=V,a=A,b=B;
    m=u.size();
    
    for(int i=0;i<m;i++){
        adj[u[i]].pb({v[i],i});
        adj[v[i]].pb({u[i],i});
    }
    
    w.resize(m);
    fill(all(w),0);
    ll C=ask(w);
    int d=C/A;
    int l=0,r=m-1;
    while(l<r){
        int mid=(l+r)/2;
        fill(all(w),0);
        for(int i=0;i<=mid;i++){
            w[i]=1;
        }
        if(ask(w)>C){
            r=mid;
        }
        else{
            l=mid+1;
        }
    }
    int v1=u[l],v2=v[l];
    dep[v1]=0;
    dep[v2]=0;
    dfs(v1,v2);
    cur=1;
    dfs(v2,v1);
    fill(all(w),0);
    for(auto e:edges){
        w[e]=1;
    }
    ll cost=ask(w);
    int dep1=(cost-C)/(ll)(b-a);
    int dep2=d-dep1-1;
    vector<int>ver;
    for(auto i:L){
        if(dep[i]==dep1){
            ver.pb(i);
        }
    }
    l=0,r=ver.size()-1;
    while(l<r){
        int mid=(l+r)/2;
        fill(all(w),0);
        for(int i=0;i<=mid;i++){
            w[edge[ver[i]]]=1;
        }
        if(ask(w)>C){
            r=mid;
        }
        else{
            l=mid+1;
        }
    }
    int S=ver[l];
    ver.clear();
    for(auto i:R){
        if(dep[i]==dep2){
            ver.pb(i);
        }
    }
    l=0,r=ver.size()-1;
    while(l<r){
        int mid=(l+r)/2;
        fill(all(w),0);
        for(int i=0;i<=mid;i++){
            w[edge[ver[i]]]=1;
        }
        if(ask(w)>C){
            r=mid;
        }
        else{
            l=mid+1;
        }
    }
    int T=ver[l];
    answer(S,T);
    return;
}

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