제출 #957802

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
957802		Trisanu_Das	경주 (Race) (IOI11_race)	C++17	0 / 100	4 ms	21336 KiB

race

#include <bits/stdc++.h>
#include "race.h"
using namespace std;
#define int long long
#define ff first
#define ss second
 
vector<pair<int, int> > adj[200005];
map<int, int> sum_to_dist[200005];
int sum[200005], dist[200005], N, K, ans;
 
void dfs(int u, int p, int s, int d){
  sum_to_dist[u][s] = d;
  sum[u] = s;
  dist[u] = d;
  for(auto v : adj[u]) if(v.ff != p) dfs(v.ff, u, s + v.ss, d + 1);
}
 
void merge_dfs(int u, int p){
  int target = K + 2 * sum[u];
  for(auto v : adj[u]){
    if(v.ff == p) continue;
    merge_dfs(v.ff, u);
    if(sum_to_dist[v.ff].size() > sum_to_dist[u].size()) swap(sum_to_dist[v.ff], sum_to_dist[u]);
    for(auto p : sum_to_dist[v.ff]) if(sum_to_dist[u].find(target - p.ff) != sum_to_dist[u].end()) ans = min(ans, sum_to_dist[u][target - p.ff] + p.ss - 2 * dist[u]);
    for(auto p : sum_to_dist[v.ff]){
      if(sum_to_dist[u].find(p.ff) == sum_to_dist[u].end()) sum_to_dist[u].insert(p);
      else sum_to_dist[u][p.ff] = min(sum_to_dist[u][p.ff], p.ss);
    }
  }
}
 
signed best_path(signed n, signed k, signed h[][2], signed l[]){
  N = n; K = k;
  for(int i = 0; i < n - 1; i++){
    int u = h[i][0], v = h[i][1], w = l[i];
    adj[u].push_back({v, w});
    adj[v].push_back({u, w});
  }
  dfs(0, -1, 0, 0);
  merge_dfs(0, -1);
  return ans == INT_MAX ? -1 : ans;
}

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