Submission #865979

#	Time	Username	Problem	Language	Result	Execution time	Memory
865979		yeediot	경주 (Race) (IOI11_race)	C++17	0 / 100	2 ms	10548 KiB

race

#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
//Don't open the standings during contests.
const int mxn=2e5+5;
vector<pii>adj[mxn];
int cnt[mxn];
bool vis[mxn];
void cnt_sz(int v,int pa){
    cnt[v]=1;
    for(auto [u,d]:adj[v]){
        if(vis[u] or u==pa)continue;
        cnt_sz(u,v);
        cnt[v]+=cnt[u];
    }
}
int find(int v,int pa,int tar){
    for(auto [u,d]:adj[v]){
        if(vis[u] or u==pa)continue;
        if(cnt[u]*2>tar)return find(u,v,tar);
    }
    return v;
}
int ans=1e9;
vector<pii>dis;
void dfs(int v,int pa,int l,int len,int k){
    //cout<<v<<' '<<l<<' '<<len<<'\n';
    if(l>k)return;
    dis.pb({l,len});
    for(auto [u,d]:adj[v]){
        if(vis[u] or u==pa)continue;
        dfs(u,v,l+1,len+d,k);
    }
}
int f[mxn];
void cd(int v,int k,int n){
    cnt_sz(v,v);
    v=find(v,v,cnt[v]);
    vis[v]=1;
    vector<int>undo;
    for(auto [u,d]:adj[v]){
        if(vis[u])continue;
        dis.clear();
        dis.pb({0,0});
        dfs(u,v,1,d,k);
        for(int j=0;j<sz(dis);j++){
            chmin(ans,f[k-dis[j].S]+dis[j].F);
           // cout<<u<<' '<<dis[j].S<<' '<<dis[j].F<<' '<<f[k-dis[j].S]<<' '<<ans<<'\n';
        }
        for(int j=0;j<sz(dis);j++){
            undo.pb(dis[j].S);
            chmin(f[dis[j].S],dis[j].F);
        }
    }
    for(auto x:undo)f[x]=1e9;
    for(auto [u,d]:adj[v]){
        if(vis[u])continue;
        cd(u,k,n);
    }
}
int best_path(int N,int K,int H[][2],int L[]){
    for(int i=0;i<N-1;i++){
        adj[H[i][0]].pb({H[i][1],L[i]});
        adj[H[i][1]].pb({H[i][0],L[i]});
    }
    for(int i=0;i<=K;i++){
        f[i]=1e9;
    }
    cd(0,K,N);
    return (ans==1e9?-1:ans);
}
/*signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    int n,k;
    cin>>n>>k;
    int h[n-1][2];
    int l[n-1];
    for(int i=0;i<n-1;i++){
        cin>>h[i][0]>>h[i][1];
    }
    for(int i=0;i<n-1;i++){
        cin>>l[i];
    }
    cout<<best_path(n,k,h,l);
}*/
 /*
 input:
  11 12
  0 1
  0 2
  2 3
  3 4
  4 5
  0 6
  6 7
  6 8
  8 9
  8 10
  3
  4
  5
  4
  6
  3
  2
  5
  6
  7
*/

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