#503757 (C++14) No.1094 木登り / Climbing tree

• 問題: No.1094 木登り / Climbing tree
• ユーザー: fine
• 提出日時: 2020-06-27 00:05:14
• 言語: C++14 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 620 ms / 2,000 ms
• コード長: 2,329 bytes
• コンパイル時間: 2,590 ms
• コンパイル使用メモリ: 184,268 KB
• 実行使用メモリ: 60,336 KB
• 最終ジャッジ日時: 2024-11-08 06:09:27
• 合計ジャッジ時間: 17,670 ms
• ジャッジサーバーID （参考情報）: judge2 / judge1

ファイルパターン	結果
sample	AC * 1
other	AC * 26

ソースコード

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#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, ll>;
constexpr char newl = '\n';
struct LCA {
    using Graph = vector< vector<int> >;
    const Graph& g;
    const int LOGV;
    const int root;
    vector< vector<int> > parent;
    vector<int> depth;
    LCA(const Graph& g, int root = 0) : g(g), LOGV(32 - __builtin_clz(g.size())), root(root) {
        int V = g.size();
        parent.resize(LOGV, vector<int>(V));
        depth.resize(V);
        dfs(root, -1, 0);
        for (int k = 0; k + 1 < LOGV; k++) {
            for (int v = 0; v < V; v++) {
                if (parent[k][v] < 0) parent[k + 1][v] = -1;
                else parent[k + 1][v] = parent[k][parent[k][v]];
            }
        }
    }
    void dfs(int v, int p, int d) {
        parent[0][v] = p;
        depth[v] = d;
        for (int i : g[v]) {
            if (i != p) dfs(i, v, d + 1);
        }
    }
    int operator()(int u, int v) const {
        if (depth[u] > depth[v]) swap(u, v);
        for (int k = 0; k < LOGV; k++) {
            if ((depth[v] - depth[u]) >> k & 1) {
                v = parent[k][v];
            }
        }
        if (u == v) return u;
        for (int k = LOGV - 1; k >= 0; k--) {
            if (parent[k][u] != parent[k][v]) {
                u = parent[k][u];
                v = parent[k][v];
            }
        }
        return parent[0][u];
    }
};
using GraphW = vector< vector<P> >;
void dfs(int cur, int par, const GraphW& g, vector<ll>& d) {
    for (const P& p : g[cur]) {
        if (p.first == par) continue;
        d[p.first] = d[cur] + p.second;
        dfs(p.first, cur, g, d);
    }
}
int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    LCA::Graph g(n);
    GraphW g2(n);
    for (int i = 1; i < n; i++) {
        int a, b;
        ll c;
        cin >> a >> b >> c;
        --a; --b;
        g[a].push_back(b);
        g[b].push_back(a);
        g2[a].emplace_back(b, c);
        g2[b].emplace_back(a, c);
    }
    LCA lca(g);
    vector<ll> d(n, 0);
    dfs(0, -1, g2, d);
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        int s, t;
        cin >> s >> t;
        --s; --t;
        int l = lca(s, t);
        cout << d[s] + d[t] - d[l] * 2 << newl;
    }
    return 0;
}
 
 
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