Submission #933903

#	Time	Username	Problem	Language	Result	Execution time	Memory
933903		kim	Highway Tolls (IOI18_highway)	C++17	30 / 100	194 ms	12928 KiB

highway

#include "highway.h"
#include<bits/stdc++.h>
using namespace std;
#define eb emplace_back
using ll=long long;
using pii=pair<int,int>;
#define f first
#define s second

int n,m;
pii edge[130005];
vector<pii> graph[90005];
vector<int> tmp,ans;
ll mn_ask,dist;
bitset<90005> vis;
int tour[90005];

void solve1(int U){
    int id=0;
    queue<int> q;
    q.emplace(U);
    vis=0;
    vis[U]=1;
    tour[U]=0;
    while(q.size()){
        int u=q.front(); q.pop();
        for(auto &[v,i]:graph[u]){
            if(vis[v]) continue;
            vis[v]=1;
            q.emplace(v);
            tour[v]=++id;
        }
    }
    int l=1,r=id;
    while(l<r){
        int mid=l+r>>1;
        for(int i=0;i<m;++i){
            auto &[u,v]=edge[i];
            if(tour[u]<=mid&&tour[v]<=mid) tmp[i]=0;
            else tmp[i]=1;
        }
        if(ask(tmp)==mn_ask) r=mid;
        else l=mid+1;
    }
    for(int i=0;i<n;++i){
        if(tour[i]==l){
            ans.eb(i);
            return;
        }
    }
}
void solve2(int U){
    int id=0;
    queue<pii> q;
    q.emplace(U,0);
    vis=0;
    vis[U]=1;
    tour[U]=0;
    while(q.size()){
        auto [u,d]=q.front(); q.pop();
        for(auto &[v,i]:graph[u]){
            if(vis[v]) continue;
            vis[v]=1;
            if(d+1<dist) q.emplace(v,d+1);
            tour[v]=++id;
        }
    }
    int l=dist,r=id;
    while(l<r){
        int mid=l+r>>1;
        for(int i=0;i<m;++i){
            auto &[u,v]=edge[i];
            if(tour[u]<=mid&&tour[v]<=mid) tmp[i]=0;
            else tmp[i]=1;
        }
        if(ask(tmp)==mn_ask) r=mid;
        else l=mid+1;
    }
    for(int i=0;i<n;++i){
        if(tour[i]==l){
            ans.eb(i);
            return;
        }
    }
}
void solve3(int U){
    queue<pii> q;
    q.emplace(U,0);
    vis=0;
    vis[U]=1;
    vector<int> tmp2(tmp.size(),1);
    vector<pii> vec;
    while(q.size()){
        auto [u,d]=q.front(); q.pop();
        for(auto &[v,id]:graph[u]){
            if(vis[v]) continue;
            if(d+1<dist) q.emplace(v,d+1), tmp2[id]=0;
            else if(d+1==dist) vec.eb(v,id);
            vis[v]=1;
        }
    }
    int l=0,r=vec.size();
    while(l<r){
        int mid=l+r>>1;
        tmp=tmp2;
        for(int i=0;i<=mid;++i) tmp[vec[i].s]=0;
        if(ask(tmp)==mn_ask) r=mid;
        else l=mid+1;
    }
    ans.eb(vec[l].f);
}

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    n=N,m=U.size();
    for(int i=0;i<m;++i){
        edge[i]={U[i],V[i]};
        graph[U[i]].eb(V[i],i);
        graph[V[i]].eb(U[i],i);
    }
    tmp.assign(m,0);
    mn_ask=ask(tmp), dist=mn_ask/A;
    solve1(0);
    solve2(ans[0]);
    solve3(ans[1]);
    answer(ans[1],ans[2]);
}
/*
15 15  99 100  9 10
0 1
1 3
3 5
5 7
7 9
9 11
11 13
13 14
14 12
12 10
10 8
8 6
6 4
4 2
2 0
*/

Compilation message (stderr)

highway.cpp: In function 'void solve1(int)':
highway.cpp:36:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   36 |         int mid=l+r>>1;
      |                 ~^~
highway.cpp: In function 'void solve2(int)':
highway.cpp:70:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   70 |         int mid=l+r>>1;
      |                 ~^~
highway.cpp: In function 'void solve3(int)':
highway.cpp:104:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  104 |         int mid=l+r>>1;
      |                 ~^~

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