Submission #848688

#	Time	Username	Problem	Language	Result	Execution time	Memory
848688		efedmrlr	Race (IOI11_race)	C++17	100 / 100	354 ms	33316 KiB

race

#include <bits/stdc++.h>
#include "race.h"
using namespace std;
#define lli long long int
#define MP make_pair
#define pb push_back
#define REP(i,n) for(int (i) = 0; (i) < (n); (i)++)
#pragma optimize('O1,O2,O3, Ofast');
const double EPS = 0.00001;
const int INF = 1e9+500;
const int ALPH = 26;
const int MOD = 1e9+7;
const int M = 1e6+5;
const int NMAX = 2e5+5;
int n,m,q, k;
array<int,2> cnt[M];
int ans = INF;
int vis[NMAX], subt[NMAX];
vector<vector<array<int,2> > > adj;
vector<int> centers;
int curc = 0;
inline void subtdfs(int node, int par) {
  subt[node] = 1;
  for(auto c : adj[node]) {
    if(c[0] == par) continue;
    if(vis[c[0]]) continue;
    subtdfs(c[0], node);
    subt[node] += subt[c[0]];
  }
  

}
inline int cdfs(int node, int par, int sz) {
  for(auto c : adj[node]) {
    if(c[0] == par) continue;
    if(vis[c[0]]) continue;
    if(subt[c[0]]*2 >= sz) {
      return cdfs(c[0], node, sz);
    }
  }
  return node;
}

inline void find_centroids() {
  subtdfs(1, 0);
  int tmp = cdfs(1, 0, subt[1]);
  centers.pb(tmp);
  int ind = 0;
  vis[tmp] = 1;
  while(ind < centers.size()) {
    for(auto c : adj[centers[ind]]) {
        if(vis[c[0]]) continue;
        subtdfs(c[0], 0);
        tmp = cdfs(c[0], 0, subt[c[0]]);
        vis[tmp] = 1;
        centers.pb(tmp);
      }
      ind++;
    
  }

}

inline void dfs(int node ,int par, int cost, int leng) {
  if(leng > k) return;
  if(cnt[leng][1] != curc) {
    cnt[leng] = {cost, curc};
  }
  cnt[leng][0] = min(cnt[leng][0], cost);
  for(auto c : adj[node]) {
    if(c[0] == par) continue;
    if(vis[c[0]]) continue;
    dfs(c[0], node, cost + 1, leng + c[1]);
  }

}
inline void dfs2(int node, int par, int cost, int leng) {
  if(leng > k) return;
  if(cnt[k - leng][1] == curc) {
    ans = min(ans ,cnt[k - leng][0] + cost);
  }
  for(auto c : adj[node]) {
    if(c[0] == par) continue;
    if(vis[c[0]]) continue;
    dfs2(c[0], node, cost + 1, leng + c[1]);
  }
}

inline void find_paths() {
  for(int j = 0; j<k+1; j++) {
    cnt[j][0] = INF;
    cnt[j][1] = 0;
  }
  for(int i = 0; i<=n; i++) vis[i] = 0;

  for(auto i : centers) {
    cnt[0][0] = 0; cnt[0][1] = i;
    curc = i;
    vis[i] = 1;
    for(auto c : adj[i]) {
      if(vis[c[0]]) continue;
      dfs2(c[0], i, 1, c[1]);
      dfs(c[0], i, 1, c[1]);
    }  

  }

}

int best_path(int N, int K, int H[][2], int L[])
{
  n = N;
  adj.resize(n+1); 
  k = K;
  for(int i = 0; i<n-1; i++) {
    H[i][0]++;
    H[i][1]++;
    adj[H[i][0]].pb({H[i][1], L[i]});
    adj[H[i][1]].pb({H[i][0], L[i]});
  }
  find_centroids();
  find_paths();
  if(ans == INF) ans = -1;
  return ans;
}

Compilation message (stderr)

race.cpp:8: warning: ignoring '#pragma optimize ' [-Wunknown-pragmas]
    8 | #pragma optimize('O1,O2,O3, Ofast');
      | 
race.cpp: In function 'void find_centroids()':
race.cpp:50:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   50 |   while(ind < centers.size()) {
      |         ~~~~^~~~~~~~~~~~~~~~

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