Submission #872161

#	Time	Username	Problem	Language	Result	Execution time	Memory
872161		nguyentunglam	Cities (BOI16_cities)	C++17	100 / 100	1470 ms	46228 KiB

cities

#include<bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define endl "\n"
using namespace std;

const int N = 1e5 + 10;

long long f[1 << 5][N];

vector<pair<int, int> > adj[N];

int32_t main() {
  #define task ""

  cin.tie(0) -> sync_with_stdio(0);

  if (fopen("task.inp", "r")) {
    freopen("task.inp", "r", stdin);
    freopen("task.out", "w", stdout);
  }

  if (fopen(task".inp", "r")) {
    freopen (task".inp", "r", stdin);
    freopen (task".out", "w", stdout);
  }

  int n, k, m; cin >> n >> k >> m;

  memset(f, 61, sizeof(f));
  
  for(int i = 0; i < k; i++) {
    int x; cin >> x;
    f[1 << i][x] = 0;
  }

  while (m--) {
    int a, b, c; cin >> a >> b >> c;
    adj[a].emplace_back(b, c);
    adj[b].emplace_back(a, c);
  }



  for(int mask = 1; mask < (1 << k); mask++) {
    #define ii pair<long long, int> 
    priority_queue<ii, vector<ii>, greater<ii> > q;
    for(int i = 1; i <= n; i++) {
      for(int submask = mask; submask > 0; submask = submask - 1 & mask) {
        f[mask][i] = min(f[mask][i], f[submask][i] + f[mask ^ submask][i]);
      }
      q.push({f[mask][i], i});
    }

    while (!q.empty()) {
      long long cost; int u; tie(cost, u) = q.top(); q.pop();
      if (f[mask][u] != cost) continue;
      for(auto &[v, w] : adj[u]) if (f[mask][v] > cost + w) q.push({f[mask][v] = cost + w, v});
    }
  }
  long long ans = 1e18;
  for(int i = 1; i <= n; i++) ans = min(ans, f[(1 << k) - 1][i]);
  cout << ans;
}

Compilation message (stderr)

cities.cpp: In function 'int32_t main()':
cities.cpp:48:62: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   48 |       for(int submask = mask; submask > 0; submask = submask - 1 & mask) {
      |                                                      ~~~~~~~~^~~
cities.cpp:18:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |     freopen("task.inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cities.cpp:19:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |     freopen("task.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
cities.cpp:23:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |     freopen (task".inp", "r", stdin);
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cities.cpp:24:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |     freopen (task".out", "w", stdout);
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 22 / 22
• Subtask 2: 14 / 14
• Subtask 3: 15 / 15
• Subtask 4: 23 / 23
• Subtask 5: 26 / 26