Submission #806481

#	Time	Username	Problem	Language	Result	Execution time	Memory
806481		arush_agu	Valley (BOI19_valley)	C++17	100 / 100	179 ms	65564 KiB

valley

#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#ifdef DEBUG
#include <time.h>
#endif

#define all(a) (a).begin(), (a).end()
#define rev(a) (a).rbegin(), (a).rend()
#define F first
#define S second
int recur_depth = 0;
#ifdef DEBUG
#define dbg(x)                                                                 \
  {                                                                            \
    ++recur_depth;                                                             \
    auto x_ = x;                                                               \
    --recur_depth;                                                             \
    cerr << string(recur_depth, '\t') << "\e[91m" << __func__ << ":"           \
         << __LINE__ << "\t" << #x << " = " << x_ << "\e[39m" << endl;         \
  }
#else
#define dbg(x)
#endif

using namespace std;
using namespace __gnu_pbds;

typedef pair<int, int> ii;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> llll;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pair<int, int>> vii;
typedef vector<vii> vvii;

typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pair<ll, ll>> vll;
typedef vector<vll> vvll;

typedef vector<bool> vb;

template <class type1>
using ordered_set = tree<type1, null_type, less<type1>, rb_tree_tag,
                         tree_order_statistics_node_update>;

template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
  return os << '(' << p.first << ", " << p.second << ')';
}
template <typename T_container, typename T = typename enable_if<
                                    !is_same<T_container, string>::value,
                                    typename T_container::value_type>::type>
ostream &operator<<(ostream &os, const T_container &v) {
  os << '{';
  string sep;
  for (const T &x : v)
    os << sep << x, sep = ", ";
  return os << '}';
}

const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll INF = 1e18;
const ld EPS = 1e-9;

const int MAXLG = 22;

void solve() {
  ll n, s, q, e;
  cin >> n >> s >> q >> e;
  e--;

  vvl eds(n - 1);
  vvll adj(n);
  for (ll i = 0; i < n - 1; i++) {
    ll u, v, w;
    cin >> u >> v >> w;
    u--, v--;
    adj[u].push_back({v, w});
    adj[v].push_back({u, w});
    eds[i] = {u, v, w};
  }

  vb shops(n);
  for (ll i = 0; i < s; i++) {
    ll u;
    cin >> u;
    shops[--u] = 1;
  }

  ll timer = 0;
  vl tin(n), tout(n), depth(n), dist_root(n, INF), dist_shop_sub(n, INF);
  vll par(n, {-1, -1});
  function<void(ll, ll, ll)> f = [&](ll u, ll p, ll d) {
    depth[u] = d;
    tin[u] = timer++;
    if (shops[u])
      dist_shop_sub[u] = 0;
    for (auto [v, w] : adj[u])
      if (v != p) {
        par[v] = {u, w};
        dist_root[v] = dist_root[u] + w;
        f(v, u, d + 1);
        dist_shop_sub[u] = min(dist_shop_sub[u], dist_shop_sub[v] + w);
      }
    tout[u] = timer++;
  };
  dist_root[e] = 0;
  f(e, -1, 0);

  vvl up(MAXLG, vl(n, -1));
  for (int i = 0; i < n; i++)
    up[0][i] = par[i].first;
  for (int j = 1; j < MAXLG; j++)
    for (int i = 0; i < n; i++)
      if (up[j - 1][i] != -1)
        up[j][i] = up[j - 1][up[j - 1][i]];

  vvl st(MAXLG, vl(n, INF));
  for (int i = 0; i < n; i++)
    st[0][i] = dist_shop_sub[i] >= INF ? INF : dist_shop_sub[i] - dist_root[i];
  for (int j = 1; j < MAXLG; j++)
    for (int i = 0; i < n; i++)
      if (up[j - 1][i] != -1)
        st[j][i] = min(st[j - 1][i], st[j - 1][up[j - 1][i]]);

  auto is_anc = [&](ll u, ll v) {
    return tin[u] <= tin[v] && tout[v] <= tout[u];
  };

  while (q--) {
    ll i, r;
    cin >> i >> r;
    i--, r--;

    ll del_p = eds[i][0], del_u = eds[i][1];
    if (del_u == par[del_p].first)
      swap(del_p, del_u);

    if (!is_anc(del_u, r)) {
      cout << "escaped\n";
      continue;
    }

    if (s == n) {
      cout << "0\n";
      continue;
    }

    ll ans = INF;
    ll k = depth[r] - depth[del_u] + 1;
    ll u = r;
    for (int i = MAXLG - 1; i >= 0; i--)
      if (k & (1 << i))
        ans = min(ans, st[i][u]), u = up[i][u];
    if (ans >= INF)
      cout << "oo\n";
    else
      cout << ans + dist_root[r] << "\n";
  }
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);

  clock_t start = clock();

  int test_cases = 1;
  // cin >> test_cases;

  while (test_cases--)
    solve();

#ifdef DEBUG
  cerr << fixed << setprecision(10)
       << "\nTime Taken: " << (double)(clock() - start) / CLOCKS_PER_SEC
       << "s\n";
#endif
  return 0;
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:193:11: warning: unused variable 'start' [-Wunused-variable]
  193 |   clock_t start = clock();
      |           ^~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41