Submission #881449

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
881449	2023-12-01T08:58:31 Z	andrei_boaca	Highway Tolls (IOI18_highway)	C++17	6 / 100	74 ms	12440 KB

highway

#include "highway.h"
#include <bits/stdc++.h>
//#include "grader.cpp"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());
int n,m,niv[100005],roots[5];
ll dist,AA,BB,d[3][100005];
int where[100005];
vector<pii> muchii[100005];
vector<pii> g;
vector<int> w;
ll memo[100005],calls;
bool inarb[300005],inx[300005];
void bfs(int ind)
{
    for(int i=0;i<n;i++)
        d[ind][i]=1e9;
    d[ind][roots[ind]]=0;
    queue<int> coada;
    coada.push(roots[ind]);
    while(!coada.empty())
    {
        int nod=coada.front();
        coada.pop();
        for(auto i:muchii[nod])
            if(d[ind][i.first]>d[ind][nod]+1)
            {
                d[ind][i.first]=d[ind][nod]+1;
                coada.push(i.first);
            }
    }
}
ll buildniv(ll nivmax,ll ind)
{
    for(int i=0;i<m;i++)
    {
        if(inarb[i]==0)
        {
            w[i]=1;
            continue;
        }
        int a=g[i].first,b=g[i].second;
        if(max(d[ind][a],d[ind][b])<=nivmax)
            w[i]=0;
        else
            w[i]=1;
    }
    return ask(w);
}
ll buildx()
{
    for(int i=0;i<m;i++)
    {
        if(inarb[i]==0)
        {
            w[i]=0;
            continue;
        }
        int a=g[i].first,b=g[i].second;
        if(inx[a]||inx[b])
            w[i]=0;
        else
            w[i]=1;
    }
    return ask(w);
}
int plsfind(int ind)
{
    for(int i=0;i<m;i++)
        inarb[i]=0;
    for(int i=0;i<n;i++)
        d[ind][i]=1e9;
    ll nivmax=0;
    d[ind][roots[ind]]=0;
    queue<int> coada;
    coada.push(roots[ind]);
    while(!coada.empty())
    {
        int nod=coada.front();
        nivmax=max(nivmax,d[ind][nod]);
        coada.pop();
        for(auto i:muchii[nod])
            if(where[i.first]==ind&&d[ind][i.first]>d[ind][nod]+1)
            {
                d[ind][i.first]=d[ind][nod]+1;
                inarb[i.second]=1;
                coada.push(i.first);
            }
    }
    bool ok=0;
    if(ind==2)
        ok=1;
    int myniv=0;
    int st=0;
    int dr=min(nivmax,dist);
    while(st<=dr)
    {
        int mij=(st+dr)/2;
        ll val=buildniv(mij,ind);
        if(val==(dist-mij)*BB+mij*AA)
        {
            myniv=mij;
            st=mij+1;
        }
        else
            dr=mij-1;
    }
    vector<int> cand;
    for(int i=0;i<n;i++)
        if(d[ind][i]==myniv&&where[i]==ind)
            cand.push_back(i);
    while(true)
    {
        if(cand.size()==1)
            return cand[0];
        int lg=cand.size();
        vector<int> x,y;
        for(int i=0;i<n;i++)
            inx[i]=0;
        for(int i=0;i<cand.size();i++)
        {
            if(i<lg/2)
            {
                x.push_back(cand[i]);
                inx[i]=1;
            }
            else
                y.push_back(cand[i]);
        }
        ll val=buildx();
        if(val<dist*BB)
            cand=x;
        else
            cand=y;
    }
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B)
{
    AA=A;
    BB=B;
    n=N;
    m=U.size();
    for(int i=0;i<m;i++)
    {
        int a=U[i],b=V[i];
        g.push_back({a,b});
        muchii[a].push_back({b,i});
        muchii[b].push_back({a,i});
    }
    w.resize(m);
    dist=ask(w)/A;
    ll st=0;
    ll dr=m-1;
    while(st<=dr)
    {
        ll mij=(st+dr)/2;
        for(int i=0;i<m;i++)
        {
            if(i<=mij)
                w[i]=1;
            else
                w[i]=0;
        }
        ll val=ask(w);
        if(val>dist*A)
        {
            roots[1]=g[mij].first;
            roots[2]=g[mij].second;
            dr=mij-1;
        }
        else
            st=mij+1;
    }
    bfs(1);
    bfs(2);
    for(int i=0;i<n;i++)
    {
        if(d[1][i]<d[2][i])
            where[i]=1;
        if(d[2][i]<d[1][i])
            where[i]=2;
    }
    int S=plsfind(1);
    int T=plsfind(2);
    answer(S,T);
}

Compilation message

highway.cpp: In function 'int plsfind(int)':
highway.cpp:122:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  122 |         for(int i=0;i<cand.size();i++)
      |                     ~^~~~~~~~~~~~
highway.cpp:92:10: warning: variable 'ok' set but not used [-Wunused-but-set-variable]
   92 |     bool ok=0;
      |          ^~

Subtask #1
0 / 5.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	6620 KB	Output is correct
2	Correct	1 ms	6612 KB	Output is correct
3	Incorrect	1 ms	6616 KB	Output is incorrect: {s, t} is wrong.
4	Halted	0 ms	0 KB	-

Subtask #2
0 / 7.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	6672 KB	Output is correct
2	Incorrect	15 ms	7288 KB	Output is incorrect: {s, t} is wrong.
3	Halted	0 ms	0 KB	-

Subtask #3
6.0 / 6.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	14 ms	7292 KB	Output is correct
2	Correct	21 ms	7804 KB	Output is correct
3	Correct	27 ms	8608 KB	Output is correct
4	Correct	69 ms	12440 KB	Output is correct
5	Correct	62 ms	11968 KB	Output is correct
6	Correct	66 ms	11952 KB	Output is correct
7	Correct	74 ms	11948 KB	Output is correct
8	Correct	66 ms	12412 KB	Output is correct
9	Correct	57 ms	12072 KB	Output is correct