oj.uz

답안 #402959

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
402959 2021-05-12T15:34:19 Z rama_pang Valley (BOI19_valley) C++17
100 / 100
 296 ms 46504 KB 
#include <bits/stdc++.h>
using namespace std;

using lint = long long;
const lint INF = 1e18;

const int LOG = 18;

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

  int N, S, Q, E;
  cin >> N >> S >> Q >> E;
  E--;

  vector<pair<int, int>> edges;
  vector<vector<pair<int, int>>> adj(N);
  for (int i = 1; i < N; i++) {
    int u, v, w;
    cin >> u >> v >> w;
    u--, v--;
    edges.emplace_back(u, v);
    adj[u].emplace_back(v, w);
    adj[v].emplace_back(u, w);
  }

  vector<int> depth(N);
  vector<lint> dp(N, INF);
  vector<lint> dist(N, 0);
  vector<vector<int>> par(LOG, vector<int>(N, -1));
  vector<vector<lint>> lift(LOG, vector<lint>(N, INF));

  for (int i = 0; i < S; i++) {
    int x;
    cin >> x;
    dp[--x] = 0;
  }

  const auto Dfs = [&](const auto &self, int u, int p) -> void {
    par[0][u] = p;
    vector<pair<lint, int>> ls;
    ls.emplace_back(dp[u], u);
    for (auto [v, w] : adj[u]) if (v != p) {
      dist[v] = dist[u] + w;
      depth[v] = depth[u] + 1;
      self(self, v, u);
      ls.emplace_back(dp[v] + w, v);
      dp[u] = min(dp[u], dp[v] + w);
    }
    sort(begin(ls), end(ls));
    for (auto [v, w] : adj[u]) if (v != p) {
      lift[0][v] = (ls[0].second == v ? ls[1].first : ls[0].first) - dist[u];
    }
  };

  Dfs(Dfs, E, -1);
  for (int j = 1; j < LOG; j++) {
    for (int u = 0; u < N; u++) {
      par[j][u] = par[j - 1][u];
      lift[j][u] = lift[j - 1][u];
      if (par[j - 1][u] != -1) {
        par[j][u] = par[j - 1][par[j - 1][u]];
        lift[j][u] = min(lift[j][u], lift[j - 1][par[j - 1][u]]);
      }
    }
  }

  const auto IsAncestor = [&](int x, int y) -> bool { // is x ancestor of y?
    if (depth[x] > depth[y]) return false;
    int d = depth[y] - depth[x];
    for (int i = 0; i < LOG; i++) {
      if ((d >> i) & 1) {
        y = par[i][y];
      }
    }
    return x == y;
  };

  const auto GetMinCost = [&](int u, int d) -> lint {
    if (d < 0) return INF;
    lint ans = INF;
    for (int i = 0; i < LOG; i++) {
      if ((d >> i) & 1) {
        ans = min(ans, lift[i][u]);
        u = par[i][u];
      }
    }
    ans = min(ans, lift[0][u]);
    return ans;
  };

  while (Q--) {
    int i, r;
    cin >> i >> r;
    i--, r--;
    if (IsAncestor(edges[i].first, r) && IsAncestor(edges[i].second, r)) {
      int d = depth[r] - max(depth[edges[i].first], depth[edges[i].second]);
      lint ans = min(dp[r], dist[r] + GetMinCost(r, d - 1));
      if (ans > (INF / 100)) {
        cout << "oo\n";
      } else {
        cout << ans << '\n';
      }
    } else {
      cout << "escaped\n";
    }
  }
  return 0;
}

Subtask #1
9.0 / 9.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 460 KB Output is correct
2 Correct 4 ms 460 KB Output is correct
3 Correct 4 ms 460 KB Output is correct
4 Correct 4 ms 468 KB Output is correct

Subtask #2
27.0 / 27.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 460 KB Output is correct
2 Correct 4 ms 460 KB Output is correct
3 Correct 4 ms 460 KB Output is correct
4 Correct 4 ms 468 KB Output is correct
5 Correct 2 ms 588 KB Output is correct
6 Correct 2 ms 588 KB Output is correct
7 Correct 2 ms 588 KB Output is correct
8 Correct 2 ms 588 KB Output is correct
9 Correct 2 ms 588 KB Output is correct
10 Correct 2 ms 588 KB Output is correct
11 Correct 2 ms 588 KB Output is correct
12 Correct 2 ms 588 KB Output is correct
13 Correct 2 ms 588 KB Output is correct
14 Correct 3 ms 588 KB Output is correct

Subtask #3
23.0 / 23.0

# 결과 실행 시간 메모리 Grader output
1 Correct 169 ms 35376 KB Output is correct
2 Correct 168 ms 35068 KB Output is correct
3 Correct 180 ms 35020 KB Output is correct
4 Correct 214 ms 39352 KB Output is correct
5 Correct 198 ms 39300 KB Output is correct
6 Correct 296 ms 44876 KB Output is correct

Subtask #4
41.0 / 41.0

# 결과 실행 시간 메모리 Grader output
1 Correct 4 ms 460 KB Output is correct
2 Correct 4 ms 460 KB Output is correct
3 Correct 4 ms 460 KB Output is correct
4 Correct 4 ms 468 KB Output is correct
5 Correct 2 ms 588 KB Output is correct
6 Correct 2 ms 588 KB Output is correct
7 Correct 2 ms 588 KB Output is correct
8 Correct 2 ms 588 KB Output is correct
9 Correct 2 ms 588 KB Output is correct
10 Correct 2 ms 588 KB Output is correct
11 Correct 2 ms 588 KB Output is correct
12 Correct 2 ms 588 KB Output is correct
13 Correct 2 ms 588 KB Output is correct
14 Correct 3 ms 588 KB Output is correct
15 Correct 169 ms 35376 KB Output is correct
16 Correct 168 ms 35068 KB Output is correct
17 Correct 180 ms 35020 KB Output is correct
18 Correct 214 ms 39352 KB Output is correct
19 Correct 198 ms 39300 KB Output is correct
20 Correct 296 ms 44876 KB Output is correct
21 Correct 145 ms 34980 KB Output is correct
22 Correct 149 ms 34524 KB Output is correct
23 Correct 189 ms 34504 KB Output is correct
24 Correct 203 ms 39508 KB Output is correct
25 Correct 247 ms 46504 KB Output is correct
26 Correct 137 ms 34912 KB Output is correct
27 Correct 150 ms 34532 KB Output is correct
28 Correct 162 ms 34512 KB Output is correct
29 Correct 199 ms 37536 KB Output is correct
30 Correct 244 ms 41160 KB Output is correct
31 Correct 172 ms 34896 KB Output is correct
32 Correct 159 ms 34540 KB Output is correct
33 Correct 176 ms 34648 KB Output is correct
34 Correct 258 ms 39080 KB Output is correct
35 Correct 235 ms 46200 KB Output is correct
36 Correct 192 ms 39296 KB Output is correct