Submission #1317980

#	Time	Username	Problem	Language	Result	Execution time	Memory
1317980		ElayV13	Race (IOI11_race)	C++20	0 / 100	1 ms	332 KiB

race

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

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

int n , k , ans = INF;
vector < pair < int , int > > G[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];
bool is_rmv[N];

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 < int , int > mn;
map < int , int > can;
void dfs(int v , int p , int nd , int wd)
{
   int need = k - wd;
   if(can[need]) ans = min(ans , nd + mn[need]);
   if(!can[wd])
   {
      can[wd] = 1;
      mn[wd] = nd;
   }
   else mn[wd] = min(mn[wd] , nd);
   for(pair < int , int > nxt : G[v])
   {
      int u = nxt.first;
      if(u != p && !is_rmv[u]) dfs(u , v , nd + 1 , wd + nxt.second);
   }
}
void build(int v)
{
   int comp_sz = gsz(v , -1);
   int centro = find_centro(v , -1 , comp_sz);
   can.clear();
   mn.clear();
   can[0] = 1;
   mn[0] = 1;
   dfs(centro , -1 , 0 , 0);
   is_rmv[centro] = 1;
   for(pair < int , int > nxt : G[centro]){
      int u = nxt.first;
      if(!is_rmv[u]) build(u);
   }
}

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

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