Submission #552990

#	Time	Username	Problem	Language	Result	Execution time	Memory
552990		beedle	Race (IOI11_race)	C++17	43 / 100	3083 ms	68948 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;

vector <ll > minlen(1000000+1,mod);
vector <ll > minlenothers(1000000+1,mod);
vector <ll > ch;
 
void setup(ll  v, ll  p, ll  width[], vector <pair<ll ,ll >> adj[])
{
    width[v]=1;
    for(auto u:adj[v])
    if(u.ff!=p)
    {
        setup(u.ff,v,width,adj);
        width[v]+=width[u.ff];
    }
}
 
ll  traverse(ll  n, ll  v, ll  p, ll  width[],vector <pair<ll ,ll >> adj[])
{
    ll  outlier=-1;
    for(auto u:adj[v])
    if(u.ff!=p)
    if(width[u.ff]>n/2)
    {
        outlier=u.ff;
        break;
    }
 
    if(outlier==-1)
    return v;
    else 
    return traverse(n,outlier,v,width,adj);
}
 
void dfs(ll  v, ll  p, ll  k, ll  &ans, vector <ll > &mydist, ll  depth,vector <pair<ll ,ll >> adj[])
{
    if(mydist[v]<=k)
    {
        ll  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, depth+1,adj);
    }
}
 
void find_children(ll  v, ll  p, vector <ll > &ch,vector <pair<ll ,ll >> adj[])
{
    ch.push_back(v);
    for(auto u:adj[v])
    if(u.ff!=p)
    find_children(u.ff,v,ch,adj);
}
 
ll  solve(ll  n, ll  k, vector <pair<ll ,ll >> adj[])
{
    if(n==1)
    return mod;
    

    ll  width[n+1];
    setup(1,-1,width,adj);
 
    ll  v=traverse(n, 1,-1,width,adj);
 
 
    vector <ll > mydist(n+1,mod);
    ll  ans=mod;
    ch.clear();

    vector <ll > revert;
 
    for(auto u:adj[v])
    {
        mydist[u.ff]=u.ss;
        dfs(u.ff,v,k,ans,mydist,1,adj);
 
        for(auto x:ch)
        {
            minlenothers[x]=min(minlenothers[x],minlen[x]);
            minlen[x]=mod;
            revert.pb(x);
        }
 
        ch.clear();
    }

    for(auto x:revert)
    minlenothers[x]=mod;

   
    for(auto u:adj[v])
    {
        find_children(u.ff,v,ch,adj);
 
        sort(all(ch));
        ll s=sz(ch);
        vector <ll > m(n+1);
        rep(i,0,s-1)
        m[ch[i]]=i+1;
 
        vector <pair<ll ,ll >> nadj[s+1];
 
        rep(i,0,s-1)
        {
            ll  vt=ch[i];
            for(auto u:adj[vt])
            if(u.ff!=v)
            {
                nadj[m[vt]].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<ll ,ll >> 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);

//     ll n,k;
//     cin>>n>>k;

//     int  h[n-1][2];
//     int  l[n-1];

//     rep(i,0,n-2)
//     {
//         cin>>h[i][0]>>h[i][1]>>l[i];
//     }

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

//     return 0;
// }

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