제출 #906632

#제출 시각아이디문제언어결과실행 시간메모리
906632duckindog구슬과 끈 (APIO14_beads)C++14
0 / 100
4 ms5980 KiB
// from duckindog wth depression #include<bits/stdc++.h> using namespace std; #define int long long using pii = pair<int, int>; const int N = 2e5 + 10; int n; vector<pii> ad[N]; int f[N][2]; void dfs(int u, int pre = 0) { int sacrifice = -1e15, none = -1e15; vector<pii> best; best.push_back({-1, 0}); best.push_back({-1, 0}); for (auto duck : ad[u]) { int v, w; tie(v, w) = duck; if (v == pre) continue; dfs(v, u); sacrifice = max(0ll, sacrifice); if (f[v][1] > 0) { sacrifice += f[v][1] + w; none = max(none, f[v][0] - f[v][1]); } else none = max(none, f[v][0] + w); best.push_back({v, w}); } f[u][1] = max(sacrifice + none, -1ll); sort(best.begin(), best.end(), [&](pii a, pii b) { int x = a.first, y = b.first; if (x == -1) return false; if (y == -1) return true; return make_pair(f[x][0] - f[x][1], a.second) > make_pair(f[y][0] - f[y][1], b.second); }); pii a, b; a = best[0], b = best[1]; if (b.first > 0) f[u][0] = f[a.first][0] + f[b.first][0] + a.second + b.second; int zeoh = 0; for (auto duck : ad[u]) { int v, w; tie(v, w) = duck; if (v == pre) continue; if (v != a.first && v != b.first && f[v][1] > 0) f[u][0] += f[v][1] + w; if (f[v][1] > 0) zeoh += f[v][1] + w; } f[u][0] = max(f[u][0], zeoh); } 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; 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}); } dfs(1); cout << f[1][0]; }

컴파일 시 표준 에러 (stderr) 메시지

beads.cpp: In function 'int32_t main()':
beads.cpp:69:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |     freopen("duck.inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
beads.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |     freopen("duck.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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