제출 #1118500

#제출 시각아이디문제언어결과실행 시간메모리
1118500Peter2017Torrent (COI16_torrent)C++14
0 / 100
1027 ms62224 KiB
#include <bits/stdc++.h> #define fi first #define se second #define ll long long #define pii pair<int,int> #define MASK(i) (1LL << (i)) #define BIT(x, i) (((x) >> (i)) & 1) #define mem(a, b) memset(a, b, sizeof(a)) #define name "test" using namespace std; const int N = 3e5 + 5; const int mod = 1e9 + 7; template <typename T1, typename T2> bool maxi(T1 &a, T2 b){if (a < b){a = b; return 1;} return 0;} template <typename T1, typename T2> bool mini(T1 &a, T2 b){if (a > b){a = b; return 1;} return 0;} int n; int s; int t; bool stop[N]; vector<int> path; vector<int> dp[N]; vector<int> adj[N]; void load(){ cin.tie(0)->sync_with_stdio(0); if (fopen(name".inp", "r")){ freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); } } void input(){ cin >> n >> s >> t; for (int i = 1; i < n; i++){ int u, v; cin >> u >> v; adj[u].push_back(v); adj[v].push_back(u); } } bool getPath(int u, int pre){ if (u == t){ path.push_back(u); return 1; } for (int v : adj[u]) if (v != pre){ if (getPath(v, u)){ path.push_back(u); return 1; } } return 0; } int dfs(int u, int pre, bool type){ dp[u].clear(); for (int v : adj[u]) if (v != pre && !stop[v]){ dp[u].push_back(dfs(v, u, type)); } sort(dp[u].begin(), dp[u].end(), greater<int>()); int res = 0; for (int i = 0; i < (int)dp[u].size(); i++) maxi(res, dp[u][i] + i + 1); if (res) cout << u << " " << res << '\n'; return res; } int cal(int j){ int ans = 0; stop[path[j + 1]] = 1; ans = dfs(s, 0, 0); stop[path[j + 1]] = 0; stop[path[j]] = 1; maxi(ans, dfs(t, 0, 1)); stop[path[j]] = 0; return ans; } void solve(){ if (s == t){ assert(false); cout << dfs(s, 0, 0); return; } getPath(s, 0); reverse(path.begin(), path.end()); int ans = cal(0); int l = 0, r = (int)path.size() - 2; while (l < r){ int m1 = (l + r) >> 1; int m2 = m1 + 1; int tmp1 = cal(m1); int tmp2 = cal(m2); mini(ans, min(tmp1, tmp2)); if (tmp1 <= tmp2) r = m1; else l = m2; } cout << ans; } int main(){ load(); input(); solve(); }

컴파일 시 표준 에러 (stderr) 메시지

torrent.cpp: In function 'void load()':
torrent.cpp:30:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |   freopen(name".inp", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
torrent.cpp:31:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |   freopen(name".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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