제출 #932250

#제출 시각아이디문제언어결과실행 시간메모리
932250MisterReaperValley (BOI19_valley)C++17
0 / 100
120 ms46928 KiB
#include <bits/stdc++.h> using i64 = long long; #define int i64 constexpr int Inf = 1E14 + 5; constexpr int N = 1E5 + 5; constexpr int L = 20; int par[N][L]; int dis[N][L]; void solve() { int n, s, q, e; std::cin >> n >> s >> q >> e; std::vector<std::array<int, 3>> edges(n - 1); std::vector<std::pair<int, int>> adj[n + 1]; for(int i = 0; i < n - 1; i++) { std::cin >> edges[i][0] >> edges[i][1] >> edges[i][2]; adj[--edges[i][0]].emplace_back(--edges[i][1], edges[i][2]); adj[edges[i][1]].emplace_back(edges[i][0], edges[i][2]); } std::vector<int> shops(n); for(int i = 0; i < s; i++) { int x; std::cin >> x; x--; shops[x] = true; } int timer = 0; std::vector<int> tin(n), tout(n), dist(n), depth(n); std::function<void(int)> dfs = [&](int node) -> void { tin[node] = ++timer; for(auto [child, d] : adj[node]) { if(tin[child] == 0) { par[child][0] = node; depth[child] = depth[node] + 1; dist[child] = dist[node] + d; dfs(child); } } tout[node] = ++timer; return; }; par[e][0] = e; dfs(--e); for(int i = 0; i < n - 1; i++) { auto &[u, v, d] = edges[i]; if(depth[u] > depth[v]) { std::swap(u, v); } } std::vector<int> magic(n, -1); dfs = [&](int node) -> void { magic[node] = Inf; for(auto [child, d] : adj[node]) { if(magic[child] == -1) { dfs(child); magic[node] = std::min(magic[node], magic[child]); } } if(shops[node]) { magic[node] = std::min(magic[node], dist[node]); } else { magic[node] = std::min(magic[node], Inf); } return; }; dfs(e); for(int node = 0; node < n; node++) { if(magic[node] != Inf) { magic[node] -= 2 * dist[node]; } //std::cerr << magic[node] << " \n"[node == n - 1]; dis[node][0] = magic[par[node][0]]; } for(int lg = 1; lg < L; lg++) { for(int i = 0; i < n; i++) { par[i][lg] = par[par[i][lg - 1]][lg - 1]; dis[i][lg] = std::min(dis[i][lg - 1], dis[par[i][lg - 1]][lg - 1]); //std::cerr << i << " " << lg << " || " << dis[i][lg - 1] << " " << dis[par[i][lg - 1]][lg - 1] << "\n"; } } for(int cCc = 1; cCc <= q; cCc++) { int I, R; std::cin >> I >> R; I--; R--; int node = edges[I][1]; //std::cerr << "query: " << cCc << " ? " << I << " " << R << " :: " << node << " -> " << tin[node] << " " << tin[R] << " " << tout[R] << " " << tout[node] << "\n"; if(tin[node] <= tin[R] && tout[R] <= tout[node]) { int ans = Inf, bef = R; for(int lg = L - 1; lg >= 0; lg--) { int nxt = par[R][lg]; if(tin[node] <= tin[nxt] && tout[nxt] <= tout[node]) { //std::cerr << "zipla: " << R << " " << lg << " -> " << nxt << " :: " << dis[R][lg] << "\n"; ans = std::min(ans, dis[R][lg]); R = nxt; } } if(ans != Inf) { std::cout << ans + dist[bef] << "\n"; } else { std::cout << "oo\n"; } } else { std::cout << "escaped\n"; } } return; } signed main() { #ifdef LOCAL freopen("in.txt", "r", stdin); freopen("out.txt", "w", stdout); #endif std::ios_base::sync_with_stdio(false); std::cin.tie(NULL); std::cout.tie(NULL); int t = 1; //std::cin >> t; for(int i = 1; i <= t; i++) { solve(); } return 0; }
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