Submission #552988

#	Time	Username	Problem	Language	Result	Execution time	Memory
552988		beedle	Race (IOI11_race)	C++17	43 / 100	3073 ms	53872 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 <int> minlen(1000000+1,mod);
vector <int> minlenothers(1000000+1,mod);
vector <int> ch;
vector <pair<int,int>> adj[200000+1];
 
void setup(int v, int p, int width[])
{
    width[v]=1;
    for(auto u:adj[v])
    if(u.ff!=p)
    {
        setup(u.ff,v,width);
        width[v]+=width[u.ff];
    }
}
 
int traverse(int n, int v, int p, int width[])
{
    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);
}
 
void dfs(int v, int p, int k, int &ans, vector <int> &mydist, int depth)
{
    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, depth+1);
    }
}
 
void find_children(int v, int p, vector <int> &ch)
{
    ch.push_back(v);
    for(auto u:adj[v])
    if(u.ff!=p)
    find_children(u.ff,v,ch);
}
 
int solve(int n, int k)
{
    if(n==1)
    return mod;
    
    // cout<<"IN"<<endl;

    int width[n+1];
    setup(1,-1,width);
 
    int v=traverse(n, 1,-1,width);
 
    // cout<<"SETUP DONE: "<<v<<endl;
 
    vector <int> mydist(n+1,mod);
    int ans=mod;
    ch.clear();

    vector <int> revert;
 
    for(auto u:adj[v])
    {
        mydist[u.ff]=u.ss;
        dfs(u.ff,v,k,ans,mydist,1);
 
        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;

    // cout<<"OUT"<<endl;
 
    // cout<<"ANS : "<<ans<<endl;
    // cout<<"SIZE : "<<n<<endl;

    vector <pair<int,int>> children=adj[v];
    
    for(auto u:children)
    {
        // cout<<"BUILDING"<<endl;
        find_children(u.ff,v,ch);
 
        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];
        vector <pair<int,int>> revert[s+1];
 
        rep(i,0,s-1)
        {
            int vt=ch[i];
            for(auto u:adj[vt])
            if(u.ff!=v)
            {
                nadj[m[vt]].pb({m[u.ff],u.ss});
            }
        }

        rep(i,1,s)
        for(auto u:adj[i])
        revert[i].pb(u);

        rep(i,1,s)
        {
            adj[i].clear();
            for(auto u:nadj[i])
            adj[i].pb(u);
        }
 
        ch.clear();

        // cout<<"BUILD DONE"<<endl;
        ans=min(ans,solve(s,k));

        rep(i,1,s)
        {
            adj[i].clear();
            for(auto u:revert[i])
            adj[i].pb(u);
        }

        // cout<<"LEFT"<<endl;
    }

    // cout<<"DONE : "<<n<<endl;
 
    return ans;
}
 
int best_path(int n, int k, int h[][2], int l[])
{
    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);
    return (x==mod?-1:x);
}
 

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