제출 #640963

#제출 시각아이디문제언어결과실행 시간메모리
640963Ez0zIOVgTsSgTTorrent (COI16_torrent)C++14
100 / 100
406 ms28448 KiB
#include<bits/stdc++.h> using namespace std; void DBG() { cerr << "]\n"; } template<class H, class... T> void DBG(H h, T... t) { cerr << h; if(sizeof...(t)) cerr << ", "; DBG(t...); } #ifdef LOCAL #define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__) #else #define dbg(...) 0 #endif // LOCAL #define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++) #define F0R(i,a) FOR(i,0,a) #define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--) #define R0F(i,a) ROF(i,0,a) #define each(e,a) for(auto &e : (a)) #define sz(v) (int)(v).size() #define all(v) (v).begin(),(v).end() #define rall(v) (v).rbegin(),(v).rend() #define pb push_back #define tcT template<class T #define nl "\n" using ll = long long; using vi = vector<int>; using pi = pair<int,int>; using str = string; tcT> using V = vector<T>; tcT> using pqg = priority_queue<T,vector<T>,greater<T>>; void setIO(string NAME = "") { cin.tie(0)->sync_with_stdio(0); if(sz(NAME)) { freopen((NAME + ".inp").c_str(),"r",stdin); freopen((NAME + ".out").c_str(),"w",stdout); } } tcT> bool ckmin(T&a, const T&b) { return b < a ? a=b,1 : 0; } tcT> bool ckmax(T&a, const T&b) { return b > a ? a=b,1 : 0; } const int MOD = 1e9 + 7; const int MX = 3e5+5; int N, A, B; vi adj[MX]; vi tmp, pathAB; int dp[MX]; void dfs(int u, int p) { tmp.pb(u); if(u == B) { pathAB = tmp; return; } each(v, adj[u]) if(v != p) { dfs(v, u); } tmp.pop_back(); } int calc(int u, int p, int blk) { dp[u] = 0; if(u == blk) return dp[u]; vi vals; each(v, adj[u]) if(v != p && v != blk) { vals.pb(calc(v, u, blk)); } sort(rall(vals)); F0R(i, sz(vals)) ckmax(dp[u], vals[i] + i + 1); return dp[u]; } void solve() { cin >> N >> A >> B; F0R(i, N-1) { int u, v; cin >> u >> v; adj[u].pb(v); adj[v].pb(u); } dfs(A, -1); int lo = 0, hi = sz(pathAB) - 2; while(lo < hi) { int mid = lo + (hi - lo + 1)/2; int resA = calc(A, -1, pathAB[mid+1]); int resB = calc(B, -1, pathAB[mid]); if(resA <= resB) lo = mid; else hi = mid-1; } int ans = max(calc(A, -1, pathAB[lo+1]), calc(B, -1, pathAB[lo])); if(lo + 2 < sz(pathAB)) ckmin(ans, max(calc(B, -1, pathAB[lo+1]), calc(A, -1, pathAB[lo+2]))); cout << ans << nl; } int main() { setIO(); int t=1; //cin>>t; while(t-->0) { solve(); } return 0; }

컴파일 시 표준 에러 (stderr) 메시지

torrent.cpp: In function 'void setIO(std::string)':
torrent.cpp:37:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         freopen((NAME + ".inp").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
torrent.cpp:38:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |         freopen((NAME + ".out").c_str(),"w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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