Submission #986677

#TimeUsernameProblemLanguageResultExecution timeMemory
986677chautanphatRace (IOI11_race)C++14
0 / 100
3 ms4956 KiB
#include "race.h" #include<bits/stdc++.h> using namespace std; const int N = 2e5, W = 1e6; int n, k, child[N], f[W], ans = N; bool del[N]; vector<pair<int, int>> a[N]; void cntSize(int u, int pre = 0) { child[u] = 1; for (int i = 0; i < (int)a[u].size(); i++) { int v = a[u][i].first; if (v == pre || del[v]) continue; cntSize(v, u); child[u] += child[v]; } } int centroid(int u, int sz, int pre = 0) { for (int i = 0; i < (int)a[u].size(); i++) { int v = a[u][i].first; if (v != pre && !del[v] && child[v] > sz/2) return centroid(v, sz, u); } return u; } void cal(int u, int dis, int mode, int pre = 0, int h = 1) { if (dis > k) return; if (!mode) ans = min(ans, h+f[k-dis]); else f[dis] = min(f[dis], h); for (int i = 0; i < (int)a[u].size(); i++) { int v = a[u][i].first, w = a[u][i].second; if (del[v] || v == pre) continue; cal(v, dis+w, mode, u, h+1); } } void reset(int u, int dis, int pre = 0) { if (dis > k) return; f[dis] = N; for (int i = 0; i < (int)a[u].size(); i++) { int v = a[u][i].first, w = a[u][i].second; if (del[v] || v == pre) continue; reset(v, dis+w, u); } } void decompose(int u) { cntSize(u); int root = centroid(u, child[u]); del[root] = 1; for (int i = 0; i < (int)a[root].size(); i++) { int v = a[root][i].first, w = a[root][i].second; if (del[v]) continue; cal(v, w, 0); cal(v, w, 1); } for (int i = 0; i < (int)a[root].size(); i++) { int v = a[root][i].first, w = a[root][i].second; if (del[v]) continue; reset(v, w); } for (int i = 0; i < (int)a[root].size(); i++) if (!del[a[root][i].first]) decompose(a[root][i].first); } int best_path(int N1, int K, int H[][2], int L[]) { for (int i = 1; i <= k; i++) f[i] = N; for (int i = 0; i < N1; i++) { a[H[i][0]].push_back({H[i][1], L[i]}); a[H[i][1]].push_back({H[i][0], L[i]}); } n = N1, k = K; decompose(0); return (ans == N ? -1 : ans); }
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