Submission #906573

#	Time	Username	Problem	Language	Result	Execution time	Memory
906573		duckindog	Beads and wires (APIO14_beads)	C++14	0 / 100	1 ms	348 KiB

beads

// from duckindog wth depression
#include<bits/stdc++.h>

using namespace std;

using pii = pair<int, int>;
const int N = 10 + 10;
int n;
pair<int, int> ed[N];
vector<pii> ad[N];

bool mk[N], dd[N];
pair<int, int> dfs(int u, int pre = 0) {
  dd[u] = 1;
  int ret = 0, cnt = 0;
  for (auto duck : ad[u]) {
    int v, w; tie(v, w) = duck;
    if (v == pre) continue;
    if (!mk[v]) continue;

    pii nret = dfs(v, u);
    ret += nret.first + w;
    cnt += nret.second + 1;
  }
  return {ret, cnt};

}

int32_t main() {
  cin.tie(0)->sync_with_stdio(0);

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

  cin >> n;
  int answer = 0;

  for (int i = 1; i < n; ++i) {
    int u, v, w; cin >> u >> v >> w;
    ad[u].push_back({v, w});
    ad[v].push_back({u, w});
    ed[i] = {u, v};
  }

  for (int mask = 1; mask < (1 << n - 1) - 1; ++mask) {
    memset(mk, 0, sizeof mk);
    memset(dd, 0, sizeof dd);
    int cnt = 0;
    for (int i = 1; i < n; ++i) {
      if (mask >> i - 1 & 1) {
        mk[ed[i].first] = mk[ed[i].second] = 1;
        cnt += 1;
      }
    }
    if (cnt & 1) continue;

    int value = 0;
    for (int i = 1; i <= n; ++i) {
      if (mk[i] && !dd[i]) {
        pii val = dfs(i);
        if (val.second & 1) {
          value = -1;
          break;
        }
        value += val.first;
      }
    }

    answer = max(answer, value);
  }
  cout << answer;

}

Compilation message (stderr)

beads.cpp: In function 'int32_t main()':
beads.cpp:47:37: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
   47 |   for (int mask = 1; mask < (1 << n - 1) - 1; ++mask) {
      |                                   ~~^~~
beads.cpp:52:21: warning: suggest parentheses around '-' inside '>>' [-Wparentheses]
   52 |       if (mask >> i - 1 & 1) {
      |                   ~~^~~
beads.cpp:33:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     freopen("duck.inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:34:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |     freopen("duck.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43