Submission #884446

#	Time	Username	Problem	Language	Result	Execution time	Memory
884446		vijay72	Fountain (eJOI20_fountain)	C++17	0 / 100	123 ms	22488 KiB

fountain

#include "bits/stdc++.h"
using namespace std;

// clang-format off

#ifdef DEBUG
    #include "debug.hpp"
#else
    #define dbg(x...) 0 
#endif

// clang-format on

struct reservoir {
  int diameter;
  int capacity;
};

using Graph = std::vector<std::vector<int>>;
class LCA {
  // largest jump will be less than 2^max_pow
  int max_pow;

  // up[x][i] = 2^xth ansector of node x
  std::vector<std::vector<int>> up;

  // capacity[x][i] -> sum of capacities from i till 2^ith ancestor but NOT
  // INCLUDING capacity of ancestor
  std::vector<std::vector<int>> capacity;

  void dfs(const Graph &G, int cur_node, int par,
           vector<reservoir> &reservoir_list) {
    up[0][cur_node] = par;

    for (auto child : G[cur_node]) {
      if (child == par) continue;

      capacity[0][child] = reservoir_list[child].capacity;
      dfs(G, child, cur_node, reservoir_list);
    }
  }

 public:
  LCA(const Graph &G, vector<reservoir> &reservoir_list)
      : max_pow(31 - __builtin_clz(G.size())),
        up(max_pow, std::vector<int>(G.size(), 0)),
        capacity(max_pow, vector<int>(G.size(), 0)) {
    dfs(G, 0, 0, reservoir_list);

    for (std::size_t x = 1; x < up.size(); x++) {
      for (std::size_t i = 1; i < G.size(); i++) {
        int mid = up[x - 1][i];
        up[x][i] = up[x - 1][mid];
        capacity[x][i] = capacity[x - 1][i] + capacity[x - 1][mid];
      }
    }
  }

  int query(int node, int water_poured) const {
    for (int i = max_pow - 1; i >= 0 && node; i--) {
      if (capacity[i][node] < water_poured) {
        water_poured -= capacity[i][node];
        node = up[i][node];
      }
    }
    return node;
  }
};

void solve() {
  int n, q;
  cin >> n >> q;

  Graph adj(n + 1);
  vector<reservoir> reservoir_list(n + 1);
  reservoir_list[0].capacity = INT_MAX / 2;
  for (int i = 1; i <= n; i++) {
    cin >> reservoir_list[i].diameter >> reservoir_list[i].capacity;
  }

  stack<pair<int, int>> st;
  for (int i = n; i >= 1; i--) {
    while (!st.empty() && st.top().first <= reservoir_list[i].diameter)
      st.pop();

    if (st.empty()) {
      adj[0].push_back(i);
      adj[i].push_back(0);
    } else {
      adj[st.top().second].push_back(i);
      adj[i].push_back(st.top().second);
    }
    st.push({reservoir_list[i].diameter, i});
  }

  LCA l(adj, reservoir_list);

  while (q--) {
    int node, water_poured;
    cin >> node >> water_poured;
    cout << l.query(node, water_poured) << "\n";
  }
}

signed main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int T = 1;
  while (T--) solve();
  return 0;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40