Submission #1000825

#	Time	Username	Problem	Language	Result	Execution time	Memory
1000825		ALTAKEXE	Race (IOI11_race)	C++17	0 / 100	1 ms	8796 KiB

race

#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int>> adj[200001];
vector<vector<pair<int, int>>> x;
vector<vector<int>> dp;
int _N, _K, mn = INT_MAX;
void dfs(int v, int p = -1)
{
  dp[v][0] = 0;
  for (auto [i, w] : adj[v])
  {
    if (i != p)
      dfs(i, v);
  }
  x.assign(_K + 1, {});
  for (auto [i, w] : adj[v])
  {
    if (i == p)
      continue;
    for (int j = w; j <= _K; j++)
    {
      if (dp[i][j - w] == INT_MAX)
        continue;
      if (x[j].size() < 2)
        x[j].push_back({dp[i][j - w] + 1, i});
      else if (dp[i][j - w] + 1 < x[j][1].first)
        x[j][1] = {dp[i][j - w] + 1, i};
      if (x[j].size() == 2 && x[j][0].first > x[j][1].first)
        swap(x[j][0], x[j][1]);
      dp[v][j] = min(dp[v][j], dp[i][j - w] + 1);
    }
  }
  if (!x[_K].empty())
    mn = min(mn, x[_K][0].first);
  for (int i = 1; i < _K; i++)
  {
    if (x[i].empty() || x[_K - i].empty())
      continue;
    if (x[i][0].second != x[_K - i][0].second)
      mn = min(mn, x[i][0].first + x[_K - i][0].first);
    else if (1 < (int)x[_K - i].size())
      mn = min(mn, x[i][0].first + x[_K - i][1].first);
  }
}
int best_path(int n, int k, int h[][2], int l[])
{
  _N = n;
  _K = k;
  for (int i = 0; i < n - 1; i++)
  {
    adj[h[i][0] + 1].push_back({h[i][1] + 1, l[i]});
    adj[h[i][1] + 1].push_back({h[i][0] + 1, l[i]});
  }
  dp.assign(n, vector<int>(k + 1, INT_MAX));
  dfs(0);
  if (mn == INT_MAX)
    return -1;
  else
    return mn;
}

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