Submission #1268620

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268620		duyanhloveav	Construction Project 2 (JOI24_ho_t2)	C++20	100 / 100	147 ms	24904 KiB

Main

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

#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1LL)

using ll = long long;

const int mxn = 9 + 1e6;
const int inf = 0x3f3f3f3f;
const ll lnf = 0x3f3f3f3f3f3f3f3f;

#define int long long

void _27augain(void) {
  int n, m;
  cin >> n >> m;
  int s, t, l, k;
  cin >> s >> t >> l >> k;
  --s, --t;
  vector<vector<array<int, 2>>> adj(n);
  for (int i = 1; i <= m; ++i) {
    int u, v, w;
    cin >> u >> v >> w;
    --u, --v;
    adj[u].push_back({v, w});
    adj[v].push_back({u, w});
  }
  auto dijkstra = [&] (int x) -> vector<int> {
    vector<int> d(n, lnf);
    priority_queue<array<int, 2>> pq;
    pq.push({d[x] = 0, x});
    while (!pq.empty()) {
      int w = -pq.top()[0], u = pq.top()[1];
      pq.pop();
      if (w > d[u]) {
        continue;
      }
      for (auto &y : adj[u]) {
        if (d[y[0]] > d[u] + y[1]) {
          d[y[0]] = d[u] + y[1];
          pq.push({-d[y[0]], y[0]});
        }
      }
    }
    return d;
  };
  vector<int> dS = dijkstra(s), dT = dijkstra(t);
  if (dS[t] <= k) {
    cout << n * (n - 1) / 2 << "\n";
    return;
  }
  int res = 0;
  vector<int> S;
  for (int i = 0; i < n; ++i) {
    if (dS[i] ^ lnf) {
      S.push_back(dS[i]);
    }
  }
  sort(begin(S), end(S));
  vector<int> T;
  for (int j = 0; j < n; ++j) {
    if (dT[j] ^ lnf) {
      T.push_back(dT[j]);
    }
  }
  sort(begin(T), end(T));
  for (auto &x : T) {
    res += upper_bound(begin(S), end(S), k - l - x) - begin(S);
  }
  cout << res << "\n";
}

int32_t main(void) {
#define task "_27augain"
  cin.tie(0)->sync_with_stdio(0);
  for (string iext : {"in", "inp"}) {
    if (fopen((task "." + iext).c_str(), "r")) {
      freopen((task "." + iext).c_str(), "r", stdin);
      freopen(task ".out", "w", stdout);
    }
  }
  int testcase = 1;
  // cin >> testcase;
  while (testcase--) {
    _27augain();
  }
  return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int32_t main()':
Main.cpp:79:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   79 |       freopen((task "." + iext).c_str(), "r", stdin);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:80:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |       freopen(task ".out", "w", stdout);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 16 / 16
• Subtask 3: 29 / 29
• Subtask 4: 47 / 47