Submission #1001682

#	Time	Username	Problem	Language	Result	Execution time	Memory
1001682		nomuluun	Race (IOI11_race)	C++14	31 / 100	410 ms	184716 KiB

race

#include <bits/stdc++.h>
using namespace std;
int k, mn = INT_MAX;
vector<vector<int>> dp(200001, vector<int>(101, INT_MAX)); // sum I and ends at node v is the minimum of the paths
vector<pair<int, int>> adj[200001];                        // save edges
vector<vector<pair<int, int>>> path;                       // keep the best paths of each weights
void dfs(int v, int p)
{
  dp[v][0] = 0;
  for (auto [i, w] : adj[v])
    if (i != p)
      dfs(i, v);
  path.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 (path[j].size() < 2)
        path[j].push_back({dp[i][j - w] + 1, i}); // keep best two paths
      else if (dp[i][j - w] + 1 < path[j][1].first)
        path[j][1] = {dp[i][j - w] + 1, i}; // keep current path
      if (path[j].size() == 2 && path[j][0].first > path[j][1].first)
        swap(path[j][0], path[j][1]); // swap shortest path
      dp[v][j] = min(dp[v][j], dp[i][j - w] + 1);
    }
  }
  if (!path[k].empty())
    mn = min(mn, path[k][0].first); // if there is any path which is exactly K
  for (int i = 1; i < k; i++)
  {
    if (path[i].empty() || path[k - i].empty())
      continue;
    if (path[i][0].second != path[k - i][0].second)
      mn = min(mn, path[i][0].first + path[k - i][0].first); // compare 2 best paths
    else if (1 < path[k - i].size())
      mn = min(mn, path[i][0].first + path[k - i][1].first); // compare 2 best paths if there is path over 1.
  }
}
int best_path(int N, int K, int H[][2], int L[])
{
  k = K;
  for (int i = 0; i < N - 1; i++)
  {
    adj[H[i][0]].push_back({H[i][1], L[i]});
    adj[H[i][1]].push_back({H[i][0], L[i]});
  }
  dfs(0, -1);
  if (mn == INT_MAX)
    return -1;
  else
    return mn;
}
#define MAX_N 500000

static int N, K;
static int H[MAX_N][2];
static int L[MAX_N];
static int solution;

Compilation message (stderr)

race.cpp: In function 'void dfs(int, int)':
race.cpp:10:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   10 |   for (auto [i, w] : adj[v])
      |             ^
race.cpp:14:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   14 |   for (auto [i, w] : adj[v])
      |             ^
race.cpp: At global scope:
race.cpp:62:12: warning: 'solution' defined but not used [-Wunused-variable]
   62 | static int solution;
      |            ^~~~~~~~
race.cpp:61:12: warning: 'L' defined but not used [-Wunused-variable]
   61 | static int L[MAX_N];
      |            ^
race.cpp:60:12: warning: 'H' defined but not used [-Wunused-variable]
   60 | static int H[MAX_N][2];
      |            ^
race.cpp:59:15: warning: 'K' defined but not used [-Wunused-variable]
   59 | static int N, K;
      |               ^
race.cpp:59:12: warning: 'N' defined but not used [-Wunused-variable]
   59 | static int N, K;
      |            ^

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