Submission #1256021

#TimeUsernameProblemLanguageResultExecution timeMemory
1256021comgaTramAnhDreaming (IOI13_dreaming)C++20
0 / 100
78 ms26896 KiB
#include <bits/stdc++.h> #include "dreaming.h" using namespace std; vector <int> listVertex; vector <vector <pair <int, int>>> adj; vector <bool> visited; vector <int> f_out, f_in; vector <vector <int>> prefix, suffix; void dfs_out(int u, int father) { listVertex.push_back(u); vector <pair <int, int>> children; visited[u] = true; for (int i = 0; i < (int) adj[u].size(); i++) { pair <int, int> neighbor = adj[u][i]; if (neighbor.first != father) { children.push_back(neighbor); } } for (int i = 0; i < (int) children.size(); i++) { dfs_out(children[i].first, u); f_out[u] = max(f_out[u], f_out[children[i].first] + children[i].second); } prefix[u].clear(); prefix[u].resize((int) children.size() + 2); prefix[u][0] = 0; for (int i = 1; i <= (int) children.size(); i++) { prefix[u][i] = max(prefix[u][i - 1], f_out[children[i - 1].first] + children[i - 1].second); } suffix[u].clear(); suffix[u].resize((int) children.size() + 2); suffix[u][(int) children.size() + 1] = 0; for (int i = (int) children.size(); i >= 1; i--) { suffix[u][i] = max(suffix[u][i + 1], f_out[children[i - 1].first] + children[i - 1].second); } } void dfs_in(int u, int father) { vector <pair <int, int>> children; for (int i = 0; i < (int) adj[u].size(); i++) { pair <int, int> neighbor = adj[u][i]; if (neighbor.first == father) { continue; } children.push_back(neighbor); } for (int i = 0; i < (int) children.size(); i++) { pair <int, int> neighbor = children[i]; f_in[neighbor.first] = max(f_in[neighbor.first], f_in[u] + neighbor.second); f_in[neighbor.first] = max(f_in[neighbor.first], max(prefix[u][i], suffix[u][i + 2]) + neighbor.second); dfs_in(neighbor.first, u); } } pair <int, int> solve(int u) { listVertex.clear(); int n = (int) adj.size(); dfs_out(u, -1); dfs_in(u, -1); int minDist = 1000000007; int ret; for (int i = 0; i < (int) listVertex.size(); i++) { int u = listVertex[i]; if (minDist > max(f_out[u], f_in[u])) { minDist = max(f_out[u], f_in[u]); ret = u; } } return make_pair(minDist, ret); } int travelTime(int n, int m, int l, int a[], int b[], int t[]) { adj.resize(n); visited.resize(n, false); for (int i = 0; i < m; i++) { adj[a[i]].push_back(make_pair(b[i], t[i])); adj[b[i]].push_back(make_pair(a[i], t[i])); } int ans = 0; f_out.resize(n, 0); f_in.resize(n, 0); prefix.resize(n); suffix.resize(n); vector <pair <int, int>> save; for (int i = 0; i < n; i++) { if (visited[i] == false) { save.push_back(solve(i)); } } sort(save.begin(), save.end()); ans = save.back().first; int minDist = 1000000007; if ((int) save.size() >= 2) { minDist = save.back().first + l + save[(int) save.size() - 2].first; } ans = max(ans, minDist); return ans; }
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