Submission #721179

#	Time	Username	Problem	Language	Result	Execution time	Memory
721179		victor_gao	Highway Tolls (IOI18_highway)	C++17	100 / 100	241 ms	16272 KiB

highway

#include "highway.h"
#include<bits/stdc++.h>
#define ll long long
#define pii pair<ll,ll>
#define x first
#define y second
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
vector<pii>g[90015];
vector<ll>all[90015];
vector<int>qry,R1,R2;
ll n,m,mn,a,b,d,fa[90015],dep[90015];
void bfs(int r1,int r2){
    queue<pii>q; 
    q.push({r1,r1}); q.push({r2,r2});
    dep[r1]=1; dep[r2]=1;
    while (!q.empty()){
        auto [p,root]=q.front(); q.pop();
        (root==r1 ? R1 : R2).push_back(p);
        for (auto [i,idx]:g[p]){
            if (!dep[i]){
                dep[i]=dep[p]+1; fa[i]=idx;
                q.push({i,root});
            }
        }
    }
}
void solve(int u,int v){
    fill(qry.begin(),qry.end(),1);
    bfs(u,v);
    int l=0,r=R1.size()-1;
    for (auto i:R2)
        qry[fa[i]]=0;
    while (l<r){
        int mid=(l+r)>>1;
        for (int i=1;i<=mid;i++)
            qry[fa[R1[i]]]=0;
        ll dis=ask(qry);
        if (dis==mn) r=mid;
        else l=mid+1;
        for (int i=1;i<=mid;i++)
            qry[fa[R1[i]]]=1;
    }
    int s=R1[l];
 //   cout<<"find "<<s<<'\n';
    fill(qry.begin(),qry.end(),1);
    for (auto i:R1)
        qry[fa[i]]=0;
    l=0; r=R2.size()-1;
    while (l<r){
        int mid=(l+r)>>1;
        for (int i=1;i<=mid;i++)
            qry[fa[R2[i]]]=0;
        ll dis=ask(qry);
        if (dis==mn) r=mid;
        else l=mid+1;
        for (int i=1;i<=mid;i++)
            qry[fa[R2[i]]]=1;
    }
    int t=R2[l];
 //   cout<<"answer "<<s<<" "<<t<<'\n';
    answer(s,t);
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    n=N; m=U.size(); a=A; b=B;
    for (int i=0;i<m;i++){
        g[U[i]].push_back({V[i],i});
        g[V[i]].push_back({U[i],i});
    }
    qry.resize(m,0);
    mn=ask(qry); d=mn/A;
    int l=0,r=m-1,u,v;
    while (l<r){
        int mid=(l+r)>>1;
        for (int i=0;i<=mid;i++)
            qry[i]=1;
        ll now=ask(qry);
        for (int i=0;i<=mid;i++)
            qry[i]=0;
        if (now!=mn) r=mid;
        else l=mid+1;
    }
    u=U[l]; v=V[l];
    fa[u]=l; fa[v]=l;
   // cout<<"solve "<<u<<" "<<v<<'\n';
    solve(u,v);
}
/*
./rand
./highway

*/

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