Submission #1317726

#	Time	Username	Problem	Language	Result	Execution time	Memory
1317726		ElayV13	Race (IOI11_race)	C++20	0 / 100	2 ms	568 KiB

race

#include "race.h"
#include "bits/stdc++.h"
using namespace std;

const int N = 200001;
const int INF = 1e9;

int n;
vector < pair < int , int > > G[N];
vector < pair < int , pair<int,int> > > dis[N];
void add_edge(int u,int v,int w){
   G[u].push_back({v , w});
   G[v].push_back({u , w});
}
int sub[N] , par[N] , timer = 0;
bool is_rmv[N];
int tin[N] , tout[N];

void DFS(int v , int p)
{
   par[v] = p;
   tin[v] = ++timer;
   for(pair < int , int > nxt : G[v])
   {
      int u = nxt.first;
      if(u == p) continue;
      DFS(u , v);
   }
   tout[v] = timer;
}

bool is_anc(int u , int v)
{
   return (tin[v] >= tin[u] && tout[u] >= tout[v]);
}

int gsz(int v , int p){
   sub[v] = 1;
   for(pair < int , int > nxt : G[v]){
      int u = nxt.first;
      if(u == p or is_rmv[u]) continue;
      sub[v] += gsz(u , v);
   }
   return sub[v];
}
int find_centro(int v , int p , int need){
   for(pair < int , int > nxt : G[v])
   {
      int u = nxt.first;
      if(u == p or is_rmv[u] or sub[u] <= need / 2) continue;
      return find_centro(u , v , need);
   }
   return v;
}
map < pair < int , pair < int , int > > , int > mp;
map < pair < int , pair < int , int > > , int > can;
void dfs(int v , int p , int imp , int nd , int wd , int centro)
{
   dis[v].push_back({centro , {nd,wd}});
   if(!can[{centro , {imp , wd}}])
   {
      can[{centro , {imp , wd}}] = 1;
      mp[{centro , {imp , wd}}] = INF;
   }
   mp[{centro , {imp , wd}}] = min(mp[{centro , {imp , wd}}] , nd);
   for(pair < int , int > nxt : G[v])
   {
      int u = nxt.first;
      if(u != p && !is_rmv[u]) dfs(u , v , imp , nd + 1 , wd + nxt.second , centro);
   }
}
void DFS(int centro)
{
   dis[centro].push_back({centro , {0,0}});
   for(pair < int , int > nxt : G[centro])
   {
      int u = nxt.first;
      int w = nxt.second;
      if(!is_rmv[u]) dfs(u , centro , u , 1 , w , centro);
   }
}
void build(int v)
{
   int comp_sz = gsz(v , -1);
   int centro = find_centro(v , -1 , comp_sz);
   DFS(centro);
   is_rmv[centro] = 1;
   for(pair < int , int > nxt : G[centro]){
      int u = nxt.first;
      if(!is_rmv[u]) build(u);
   }
}
int get(int v , int k)
{
   int ans = INF;
   for(pair < int , pair<int,int> > nxt : dis[v])
   {
      int centro = nxt.first;
      int dist = nxt.second.first;
      int wdist = nxt.second.second;
      int node = -1;
      int need = k - wdist;
      for(pair < int , int > U : G[centro])
      {
         if(U.first == par[centro]) continue;
         int u = U.first;
         if(is_anc(u , v)) node = u;
      }
      if(node == -1) node = par[centro];
      for(pair < int , int > U : G[centro])
      {
         if(U.first == node) continue;
         if(can[{centro , {U.first , need}}]) ans = min(ans , dist + mp[{centro , {U.first , need}}]);
      }
   }
   return ans;
}

int best_path(int N , int K , int H[][2] , int L[])
{
   n = N;
   for(int i = 0;i < N - 1;i++) add_edge(H[i][0] , H[i][1] , L[i]);
   build(0);
   DFS(0 , -1);
   int ans = INF;
   for(int i = 0;i < N;i++) ans = min(ans , get(i , K));
   if(ans == INF) ans = -1;
   return ans;
}

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