Submission #383265

#TimeUsernameProblemLanguageResultExecution timeMemory
383265Aryan_RainaRace (IOI11_race)C++14
21 / 100
3069 ms9700 KiB
#include "race.h" #include <bits/stdc++.h> using namespace std; #define ll long long #define ld long double #define ar array const int INF = 1e9; const int MOD = 1e9 + 7; int OneCentroid(int rt, vector<vector<ar<int,2>>> &g, vector<bool> &dead) { int n = g.size(); vector<int> sz(n); function<void(int,int)> get_sz = [&](int u, int pu) { sz[u] = 1; for (auto v : g[u]) if (v[1] != pu && !dead[v[1]]) { get_sz(v[1], u); sz[u] += sz[v[1]]; } }; get_sz(rt, rt); function<int(int,int)> dfs = [&](int u, int pu) { for (auto v : g[u]) if (v[1] != pu && !dead[v[1]]) { if (sz[v[1]] > sz[rt]/2) return dfs(v[1], u); } return u; }; return dfs(rt, rt); } int CentroidDecomposition(vector<vector<ar<int,2>>> &g, int k) { int n = g.size(); vector<bool> dead(n, false); vector<int> length(k+1, INF), indexes; vector<ar<int,2>> to_update; int ans = INT_MAX; function<void(int,int,int,int)> dfs = [&](int u, int pu, int len, int dist) { if (k-dist >= 0) ans = min(ans, length[k-dist] + len); to_update.push_back({dist, len}); for (auto v : g[u]) if (v[1] != pu && !dead[v[1]]) dfs(v[1], u, len + 1, dist + v[0]); }; function<void(int)> decompose = [&](int start) { int cen = OneCentroid(start, g, dead); length[0] = 0; indexes.push_back(0); // do stuff with subtree of centroid here // get length, distance to each node in subtree of centroid from centroid // ans = min(ans, length) if distance corresponding to it is k for (auto v : g[cen]) if (!dead[v[1]]) { dfs(v[1], cen, 1, v[0]); for (auto x : to_update) if (x[0] <= k) { if (length[x[0]] >= INF/2) indexes.push_back(x[0]); length[x[0]] = min(length[x[0]], x[1]); } to_update.clear(); } for (int i : indexes) length[i] = INF; indexes.clear(); dead[cen] = true; for (auto v : g[cen]) if (!dead[v[1]]) decompose(v[1]); dead[cen] = false; }; decompose(0); return (ans < INF/2) ? ans : -1; } int best_path(int N, int K, int H[][2], int L[]) { vector<vector<ar<int,2>>> g(N); for (int i = 0; i < N-1; i++) { g[H[i][0]].push_back({L[i], H[i][1]}); g[H[i][1]].push_back({L[i], H[i][0]}); } return CentroidDecomposition(g, K); }
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