Submission #657331

#	Time	Username	Problem	Language	Result	Execution time	Memory
657331		evenvalue	Sky Walking (IOI19_walk)	C++17	10 / 100	4062 ms	1048576 KiB

walk

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

template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
template<typename T>
using max_heap = priority_queue<T, vector<T>, less<T>>;

using int64 = long long;
using ld = long double;

constexpr int kInf = 1e9 + 10;
constexpr int64 kInf64 = 1e15 + 10;
constexpr int kMod = 1e9 + 7;

pair<vector<int64>, vector<int>> dijkstra(const vector<vector<pair<int, int>>> &g, const int s) {
  const int n = (int) g.size();

  vector<int64> d(n, kInf64);
  vector<int> p(n, -1);
  min_heap<pair<int64, int>> q;

  d[s] = 0;
  q.push({0, s});

  while (not q.empty()) {
    const auto [dist, x] = q.top();
    q.pop();
    if (d[x] < dist) continue;
    for (const auto &[y, w] : g[x]) {
      if (d[y] <= d[x] + w) continue;
      d[y] = d[x] + w;
      p[y] = x;
      q.push({d[y], y});
    }
  }

  return make_pair(d, p);
}

struct building {
  int x;
  int h;
};

struct skywalk {
  int i;
  int l;
  int r;
  int h;

  bool operator<(const skywalk &other) const {
    return h < other.h;
  }
};

int64 min_distance(vector<int> X, vector<int> H, vector<int> L, vector<int> R, vector<int> Y, int S, int G) {
  const int n = (int) X.size();
  const int m = (int) L.size();

  vector<building> buildings(n);
  for (int i = 0; i < n; i++) {
    buildings[i].h = H[i];
    buildings[i].x = X[i];
  }

  vector<skywalk> skywalks(m);
  for (int j = 0; j < m; j++) {
    skywalks[j].i = j;
    skywalks[j].l = L[j];
    skywalks[j].r = R[j];
    skywalks[j].h = Y[j];
  }

  sort(skywalks.begin(), skywalks.end());

  vector<vector<pair<int, int>>> g;
  vector<pair<int, int>> last(n);

  auto add_node = [&]() -> int {
    g.emplace_back();
    return (int) g.size() - 1;
  };

  auto add_edge = [&](const int x, const int y, const int w) {
    g[x].emplace_back(y, w);
    g[y].emplace_back(x, w);
  };

  for (int i = 0; i < n; i++) {
    last[i] = make_pair(add_node(), 0);
  }

  for (skywalk s : skywalks) {
    int prev = s.l;
    for (int i = s.l, x = -1; i <= s.r; i++) {
      if (s.h > buildings[i].h) continue;

      const int y = add_node();
      if (x != -1) add_edge(x, y, buildings[i].x - buildings[prev].x);
      add_edge(y, last[i].first, s.h - last[i].second);
      last[i] = make_pair(y, s.h);
      x = y;
      prev = i;
    }
  }

  const int64 ans = dijkstra(g, S).first[G];
  return (ans == kInf64 ? -1 : ans);
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 18
• Subtask 5: 0 / 43