Submission #281859

#	Time	Username	Problem	Language	Result	Execution time	Memory
281859		PKhing	Race (IOI11_race)	C++14	0 / 100	8 ms	9728 KiB

race

#include "race.h"
#include<bits/stdc++.h>
#define FOR(i,a) for(int i=0;i<a;i++)
#define FOR1(i,a) for(int i=1;i<=a;i++)
#define db(a) printf("<%d> ",a)
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define mp make_pair
#define pb emplace_back
#define p emplace
#define ii pair<long long,long long>
#define ll long long
#define rf() freopen("_working/input.in","r",stdin)
#define pf() freopen("_working/output.out","w+",stdout)
using namespace std;
const int INF=1e9;
int size[200005];
queue<ii> len;
set<ii> edge[200005];
ll ans = INF;
int centroid(int u,int p,int n){
  for(auto v:edge[u]){
    if(v.f!=p && size[v.f]>n/2)return centroid(v.f,u,n);
  }
  return u;
}
void dfs(int u,int p){
  size[u]=1;
  for(auto v:edge[u]){
    if(v.f!=p){
      dfs(v.f,u);
      size[u]+=size[v.f];
    } 
  }
}
void setlen(int u,int p,ll l,int cnt){
  len.p(l,cnt);
  for(auto v:edge[u]){
    if(v.f!=p){
      setlen(v.f,u,l+(ll)v.s,cnt+1);
    }
  }
}
ll k;
void decomp(int u,int p){
  set<ii> f,tmp;
  dfs(u,-1);
  int x = centroid(u,-1,size[u]);
  for(auto v:edge[x]){
      setlen(v.f,x,v.s,1);
    while(!len.empty()){
      tmp.p(len.front());
      auto x = f.upper_bound(mp(k-len.front().f,-1));
      if(x->f == k-len.front().f)ans = min(ans,x->s+len.front().s);
      len.pop();
    }
    for(auto i:tmp){
        f.insert(i);
    }
    tmp.clear();
  }
  for(auto v:edge[x]){
    edge[v.f].erase(mp(x,v.s));
    decomp(v.f,x);
  }
  edge[x].clear();
}
int best_path(int N, int K, int H[][2], int L[])
{
  k=K;
  for(int i=0;i<N-1;i++){
    edge[H[i][0]].p(H[i][1],L[i]);
    edge[H[i][1]].p(H[i][0],L[i]);
  }
  decomp(0,-1);
  return ans==1e9?-1:ans;
}
// int H[200005][2],L[200005];
// int N,K;
// int main(){
//   cin>>N>>K;
//   FOR(i,N-1){
//     scanf("%d %d %d",&H[i][0],&H[i][1],&L[i]);
//   }
//   printf("%d",best_path(N,K,H,L));

// }

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