# | Submission time | Handle | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
920270 | 2024-02-02T11:34:17 Z | Arp | Dreaming (IOI13_dreaming) | C++17 | 0 ms | 0 KB |
#include<bits/stdc++.h> #include"dreaming.h" using namespace std; using i64 = long long; const int N = 1e5; vector<pair<int,int>> adj[N]; i64 down[N],up[N]; bool vis[N]; i64 mini = 1e18; void dfs(int u){ vis[u] = true; vector<i64> all; i64 maxi = -1e18; for(auto [v,w] : adj[u]){ if(vis[v]) continue; // cout << u << " " << v << '\n'; down[v] = down[u] + w; dfs(v); up[u] = max(up[u],up[v] + w); } for(auto [v,w] : adj[u]){ up[v] = max(up[v],maxi + w); maxi = max(maxi,up[v] + w); } maxi = -1e18; reverse(adj[u].begin(),adj[u].end()); for(auto [v,w] : adj[u]){ up[v] = max(up[v],maxi + w); maxi = max(maxi,up[v] + w); } } void dfs2(int u,int p){ for(auto [v,w] : adj[u]){ if(v == p) continue; dfs2(v,u); } mini = min(mini,max(down[u],up[u])); } i64 travelTime(int N,int M,int L,int A[],int B[],int T[]){ for(int i = 0;i<N;i++){ up[i] = down[i] = 0; vis[i] = false; } for(int i = 0;i<M;i++){ adj[A[i]].emplace_back(B[i],T[i]); adj[B[i]].emplace_back(A[i],T[i]); } multiset<i64> ms; vector<i64> com; int cc = 0; for(int i = 0;i<N;i++){ if(!vis[i] && adj[i].size() <= 1){ mini = 1e18; dfs(i); dfs2(i,-1); ms.insert(mini); com.push_back(mini); cc ++; } } assert(cc - 1 == N - M - 1); if(cc <= 2){ i64 sum = 0; while(ms.size() > 0){ sum += *ms.begin(); ms.erase(ms.begin()); } return sum + (cc - 1) * L; } i64 ans = 1e18; for(i64 c : com){ ms.erase(ms.find(c)); i64 maxi1 = *(--ms.end()); ms.erase(ms.find(maxi1)); i64 maxi2 = *(--ms.end()); ans = min(ans,max(maxi1 + maxi2 + 2 * L,maxi1 + c + L)); ms.insert(c); ms.insert(maxi1); ms.insert(maxi2); } return ans; }