Submission #1009725

#	Time	Username	Problem	Language	Result	Execution time	Memory
1009725		asdfgrace	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	36 / 100	245 ms	262144 KiB

skyscraper

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

#define dbg(x) x
#define prt(x) dbg(cerr << x)
#define pv(x) dbg(cerr << #x << " = " << x << '\n')
#define pv2(x) dbg(cerr << #x << " = " << x.first << ',' << x.second << '\n')
#define parr(x) dbg(prt(#x << " = { "); for (auto y : x) prt(y << ' '); prt("}\n");)
#define parr2(x) dbg(prt(#x << " = { "); for (auto [y, z] : x) prt(y << ',' << z << "  "); prt("}\n");)
#define parr2d(x) dbg(prt(#x << ":\n"); for (auto arr : x) {parr(arr);} prt('\n'));
#define parr2d2(x) dbg(prt(#x << ":\n"); for (auto arr : x) {parr2(arr);} prt('\n'));

/*
can jump only multiples of 1 number
get from p0 to p1
can only jump if 0 or it was passed to you
everyone will only have it once?
can add o(m^2) edges and run dijkstra
alternatively, can add o(n^2) edges
*/

int main() {
  ios::sync_with_stdio(0); cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> a(m), b(m);
  vector<vector<array<int, 2>>> edges(n);
  for (int i = 0; i < m; i++) {
    cin >> a[i] >> b[i];
    for (int j = a[i] + b[i]; j < n; j += b[i]) {
      edges[a[i]].push_back({j, (j - a[i]) / b[i]});
    }
    for (int j = a[i] - b[i]; j >= 0; j -= b[i]) {
      edges[a[i]].push_back({j, (a[i] - j) / b[i]});
    }
  }
  priority_queue<array<int, 2>> q;
  vector<int> dist(n, 1e9);
  dist[a[0]] = 0;
  q.push({0, a[0]});
  while (q.size()) {
    int d = -q.top()[0], node = q.top()[1];
    q.pop();
    if (d != dist[node]) continue;
    for (auto [next, wt] : edges[node]) {
      if (dist[node] + wt < dist[next]) {
        dist[next] = dist[node] + wt;
        q.push({-dist[next], next});
      }
    }
  }
  cout << (dist[a[1]] == 1e9 ? -1 : dist[a[1]]) << '\n';
}

/*
any observations help

check every line
IF YOUR LINES AREN'T WRONG
CHECK IF YOUR LINES ARE IN THE RIGHT ORDER

NEVER GIVE UP
*/

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 0 / 21
• Subtask 5: 0 / 43