Submission #348489

#	Time	Username	Problem	Language	Result	Execution time	Memory
348489		juggernaut	Highway Tolls (IOI18_highway)	C++14	0 / 100	27 ms	6124 KiB

highway

#include"highway.h"
#include<bits/stdc++.h>
#ifndef EVAL
#include"grader.cpp"
#endif
using namespace std;
vector<pair<int,int>>g[90005];
vector<int>grp[90005];
bool is[90005];
int id[90005],mx,up[90005],under[90005];
long long pivot;
void dfs(int v,int p,int depth){
    mx=max(mx,depth);
    if(depth)grp[depth].push_back(id[v]);
    for(auto to:g[v])if(to.first!=p){
        id[to.first]=to.second;
        up[to.second]=to.first;
        dfs(to.first,v,depth+1);
    }
}
void go(int v,int p,int depth){
    for(auto to:g[v])if(to.first!=p){
        if(depth+1==pivot)is[to.second]=1;
        under[to.second]=to.first;
        go(to.first,v,depth+1);
    }
}
void find_pair(int n,vector<int>x,vector<int>y,int a,int b){
    for(int i=0;i<n-1;i++){
        g[x[i]].push_back({y[i],i});
        g[y[i]].push_back({x[i],i});
    }
    vector<int>v(n-1,0);
    pivot=ask(v);
    dfs(0,0,0);
    int l=1,r=mx;
    while(l<r){
        int mid=(l+r+1)>>1;
        vector<int>(n-1,0);
        for(int i=l;i<=mid;i++)for(auto to:grp[i])v[to]=1;
        if(ask(v)!=pivot)l=mid;
        else r=mid-1;
    }
    int uid=l;
    l=0,r=grp[uid].size()-1;
    while(l<r){
        int mid=(l+r)>>1;
        vector<int>v(n-1,0);
        for(int i=l;i<=mid;i++)v[grp[uid][i]]=1;
        if(ask(v)!=pivot)r=mid;
        else l=mid+1;
    }
    int s=up[grp[uid][l]];




    pivot/=a;
    go(s,s,0);
    l=0,r=n-2;
    while(l<r){
        int mid=(l+r)>>1;
        vector<int>v(n-1,0);
        for(int i=l;i<=mid;i++)v[i]=is[i];
        if(ask(v)!=pivot*a)r=mid;
        else l=mid+1;
    }
    answer(s,under[l]);
}
/*
5 4 1 2 2 4
0 1
0 2
1 3
1 4
*/

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