Submission #1226438

#	Time	Username	Problem	Language	Result	Execution time	Memory
1226438		angelolan	Race (IOI11_race)	C++20	0 / 100	0 ms	320 KiB

race

#include "race.h"
#include <bits/stdc++.h>
using namespace std;
// Pura Gente del Coach Moy y la Alexbriza
  
struct CentroidDecomposition {
  int N, K;
  vector<vector<pair<int, int>>> g;
  vector<int> sz;
  vector<bool> taken;
  vector<int> minEdges;
  int ans;
 
  CentroidDecomposition(int N, int K) : N(N), K(K), g(N), sz(N), taken(N), minEdges(K + 1, N), ans(N) {}

  void addEdge(int u, int v, int w) {
    g[u].emplace_back(v, w), g[v].emplace_back(u, w);
  }
  
  int getSize(int u, int p) {
    sz[u] = 1;
    for (auto [v, _] : g[u]) {
      if (v != p && !taken[v]) {
        sz[u] += getSize(v, u);
      }
    }
    return sz[u];
  }

  template <class F>
  void traverse(int u, int p, int l, int d, F&& f) {
    if (l > K) {
      return;
    }
    f(l, d);
    for (auto [v, w] : g[u]) {
      if (v != p && !taken[v]) {
        traverse(v, u, l + w, d + 1, f);
      }
    }
  }

  void decompose(int u, int globalSz) {
    if (globalSz == -1) {
      globalSz = getSize(u, -1);
    }
    for (auto [v, _] : g[u]) {
      if (!taken[v] && 2 * sz[v] >= globalSz) {
        sz[u] = 0;
        decompose(v, globalSz);
        return;
      }
    }

    taken[u] = true;
    for (auto [v, w] : g[u]) {
      if (!taken[v]) {
        traverse(v, u, w, 1, [&](int l, int d) { ans = min(ans, d + minEdges[K - l]); });
        traverse(v, u, w, 1, [&](int l, int d) { minEdges[l] = min(minEdges[l], d); });
      }
    }
    
    for (auto [v, _] : g[u]) {
      if (!taken[v]) {
        decompose(v, -1);
      }
    }
  }
  
  int solve() {
    minEdges[0] = 0;
    decompose(0, -1);
    return ans;
  }
};

int best_path(int N, int K, int H[][2], int L[]) {
  CentroidDecomposition cd(N, K);
  for (int i = 0; i < N - 1; ++i) {
    cd.addEdge(H[i][0], H[i][1], L[i]);
  }
  int ans = cd.solve();
  return ans == N ? -1 : ans;
}

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