Submission #1129517

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129517		MMihalev	Closing Time (IOI23_closing)	C++20	8 / 100	188 ms	45836 KiB

closing

#include "closing.h"
#include<vector>
#include<iostream>
#include<algorithm>
#include<queue>
#include<set>
#include<tuple>
using namespace std;
const int MAX_N=2e5+5;
const long long INF=(1LL<<60);
int n,x,y;
long long k;
vector<pair<int,int>>g[MAX_N];
int ans;
long long bfsdist[MAX_N];
void bfs()
{
    for(int i=0;i<n;i++)bfsdist[i]=INF;
    long long rem=k;
    int curans=0;

    bfsdist[x]=0;
    bfsdist[y]=0;
    set<pair<long long,int>>q;
    q.insert({0,x});
    q.insert({0,y});

    while(q.size())
    {
        int u,curdist;
        tie(curdist,u)=(*(q.begin()));

        if(rem>=curdist)
        {
            rem-=curdist;
            curans++;
        }
        else break;

        q.erase({curdist,u});

        for(auto [v,edge]:g[u])
        {
            long long len=bfsdist[u]+edge;
            if(len<bfsdist[v])
            {
                q.erase({bfsdist[v],v});
                bfsdist[v]=len;
                q.insert({bfsdist[v],v});
            }
        }
    }

    ans=max(ans,curans);
}

bool onpath[MAX_N];
long long otherval[MAX_N];
bool stat[MAX_N];
int parent[MAX_N];
long long paredge[MAX_N];
long long depth[MAX_N];
long long curdist;
long long distxy;
set<pair<long long,int>>s;
void dfs(int u,int par)
{
    for(auto [v,edge]:g[u])
    {
        if(v==par)continue;

        depth[v]=depth[u]+edge;
        parent[v]=u;
        paredge[v]=edge;

        dfs(v,u);
    }
}
void spread(int u,int par,long long dfsdist)
{
    otherval[u]=-curdist+distxy;
    s.insert({curdist+dfsdist,u});

    for(auto [v,edge]:g[u])
    {
        if(onpath[v] or v==par)continue;

        spread(v,u,dfsdist+edge);
    }
}
void solve()
{
    s.clear();
    for(int i=0;i<n;i++)
    {
        onpath[i]=0;
        stat[i]=0;
    }

    parent[x]=-1;
    paredge[x]=0;
    depth[x]=0;
    dfs(x,-1);

    distxy=depth[y];
    curdist=0;
    bool changed=0;

    int u=y;
    while(u!=-1)
    {
        spread(u,parent[u],0);
        curdist+=(changed==0 ? +paredge[u] : -paredge[u]);
        if(changed==0)
        {
            if(curdist>distxy-curdist)
            {
                curdist=distxy-curdist;
                changed=1;
            }
        }
        onpath[u]=1;
        u=parent[u];
    }

    long long rem=k;
    int curans=0;

    while(s.size())
    {
        auto [grab,u]=(*(s.begin()));
        s.erase({grab,u});

        if(rem>=grab)
        {
            rem-=grab;
            curans++;

            if(stat[u]==0)
            {
                s.insert({otherval[u],u});
                stat[u]=1;
            }
        }
        else break;
    }

    ans=max(ans,curans);
}
int max_score(int N, int X, int Y, long long K,std::vector<int> U, std::vector<int> V, std::vector<int> W)
{
    ans=2;n=N;x=X;y=Y;k=K;

    for(int i=0;i<n;i++)g[i].clear();

    for(int i=0;i<n-1;i++)
    {
        int u,v,w;
        u=U[i];
        v=V[i];
        w=W[i];
        g[u].push_back({v,w});
        g[v].push_back({u,w});
    }

    bfs();

    solve();

    return ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 8 / 8
• Subtask 2: 0 / 9
• Subtask 3: 0 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 9
• Subtask 6: 0 / 11
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 17