Submission #281773

#	Time	Username	Problem	Language	Result	Execution time	Memory
281773		PKhing	Race (IOI11_race)	C++14	0 / 100	146 ms	262148 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<int,int>
#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<int> sz[200005];
queue<ii> len[200005];
set<ii> edge[200005];
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,int l,int cnt,int cen){
  len[cen].p(l,cnt);
  for(auto v:edge[u]){
    if(v.f!=p){
      setlen(v.f,u,l+v.s,cnt+1,cen);
    }
  }
}
int decomp(int u,int p){
  dfs(u,-1);
  if(p!=-1)sz[p].p(size[u]);
  int x = centroid(u,-1,size[u]);
  for(auto v:edge[x]){
    setlen(v.f,x,v.s,1,x);
    edge[v.f].erase(mp(x,v.s));
    decomp(v.f,x);
  }
  edge[x].clear();
  return x;
}
int ans = INF;
void findpath(int u,int k){
  //db(u);
  int cnt = 0;
  set<ii> f,tmp;
  while(sz[u].size()>0){
    //printf("%d ",len[u].front());
    tmp.p(len[u].front());
    auto x = f.upper_bound(mp(k-len[u].front().f,-1));
    if(x->f == k-len[u].front().f)ans = min(ans,x->s+len[u].front().s);
    len[u].pop();
    cnt++;
    if(cnt==sz[u].front()){
      for(auto i:tmp){
        f.insert(i);
      }
      tmp.clear();
      cnt = 0;
      sz[u].pop();
      
      //  printf("\nchange ");
    }
  }
  //cout<<endl<<endl;
}
int best_path(int N, int K, int H[][2], int L[])
{
  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);
  FOR(i,N){
    findpath(i,K);
  }
  return ans==1e9?-1:ans;
}

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