Submission #552869

#	Time	Username	Problem	Language	Result	Execution time	Memory
552869		beedle	Race (IOI11_race)	C++17	0 / 100	1 ms	468 KiB

race

#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <set>
#include <iterator>
#include <stack>
#include <map>
#include <math.h>
#include <bitset>
#include <deque>
#include <string>
#include <tuple>
#include <queue>
#include <numeric>
#include <unordered_set>
#include <unordered_map>
#define pi 3.141592653589793238
#define ll long long
#define ld long double
#define rep(i, a, b) for (long long i = a; i <= b; i++)
#define mod 998244353ll
#define INF 1000000000000000000
#define pb push_back
#define ff first
#define ss second
#define endl '\n'
#define all(x) (x).begin (), (x).end ()
#define sz(x) (ll) (x).size ()
#define reunique(v) v.resize(std::unique(v.begin(), v.end()) - v.begin())
#define rank rnk
#define log lg
#define fast                                                                  \
    ios_base::sync_with_stdio (false);                                        \
    cin.tie (NULL);                                                           \
    cout.tie (NULL)

using namespace std;

void setup(int v, int p, int width[], vector <pair<int,int>> adj[])
{
    width[v]=1;
    for(auto u:adj[v])
    if(u.ff!=p)
    {
        setup(u.ff,v,width,adj);
        width[v]+=width[u.ff];
    }
}

int traverse(int n, int v, int p, int width[], vector <pair<int,int>> adj[])
{
    int outlier=-1;
    for(auto u:adj[v])
    if(u.ff!=p)
    if(width[u.ff]>n/2)
    outlier=u.ff;

    if(outlier==-1)
    return v;
    else 
    return traverse(n,outlier,v,width,adj);
}

void dfs(int v, int p, int k, int &ans, vector <int> &mydist, vector <int> &minlen, vector <int> &minlenothers, vector <pair<int,int>> adj[], int depth, vector <int> &ch)
{
    if(mydist[v]<=k)
    {
        int d=mydist[v];
        minlen[d]=min(minlen[d],depth);

        if(d==k)
        ans=min(ans,minlen[d]);

        ans=min(ans,depth+minlenothers[k-d]);

        ch.push_back(d);
    }

    for(auto u:adj[v])
    if(u.ff!=p)
    {
        mydist[u.ff]=mydist[v]+u.ss;
        dfs(u.ff,v,k,ans,mydist,minlen,minlenothers,adj, depth+1, ch);
    }
}

void find_children(int v, int p, vector <int> &ch, vector <pair<int,int>> adj[])
{
    ch.push_back(v);
    for(auto u:adj[v])
    if(u.ff!=p)
    find_children(u.ff,v,ch,adj);
}

int solve(int n, int k, vector <pair<int,int>> adj[])
{
    if(n==1)
    return mod;

    int width[n+1];
    setup(1,-1,width, adj);

    int v=traverse(n, 1,-1,width,adj);

    vector <int> minlenothers(k+1,mod);
    vector <int> mydist(n+1,mod);
    vector <int> minlen(k+1,mod);
    int ans=mod;
    vector <int> ch;

    for(auto u:adj[v])
    {
        mydist[u.ff]=u.ss;
        dfs(u.ff,v,k,ans,mydist,minlen,minlenothers,adj,1,ch);

        for(auto x:ch)
        {
            minlenothers[x]=min(minlenothers[x],minlen[x]);
            mydist[x]=0;
            minlen[x]=mod;
        }

        ch.clear();
    }

    for(auto u:adj[v])
    {
        find_children(u.ff,v,ch,adj);

        sort(all(ch));
        ll s=sz(ch);
        vector <int> m(n+1);
        rep(i,0,s-1)
        m[ch[i]]=i+1;

        vector <pair<int,int>> nadj[s+1];

        rep(i,0,s-1)
        {
            int v=ch[i];
            for(auto u:adj[v])
            {
                nadj[m[v]].pb({m[u.ff],u.ss});
            }
        }

        ch.clear();

        ans=min(ans,solve(s,k,nadj));
    }

    return ans;
}

int best_path(int n, int k, int h[][2], int l[])
{
    vector <pair<int,int>> adj[n+1];
    rep(i,0,n-2)
    {
        adj[h[i][0]+1].pb({h[i][1]+1,l[i]});
        adj[h[i][1]+1].pb({h[i][0]+1,l[i]});
    }

    ll x=solve(n,k,adj);
    return (x==mod?-1:x);
}

// signed main()
// {
//     fast;

//     // freopen("milkorder.in","r",stdin);
//     // freopen("milkorder.out","w",stdout);

//     int n=3;
//     int k=3;
//     int h[2][2]={{0,1},{1,2}};
//     int l[2]={1,1};

//     cout<<best_path(n,k,h,l);

//     return 0;
// }

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57