Submission #321719

#	Time	Username	Problem	Language	Result	Execution time	Memory
321719		arujbansal	Roadside Advertisements (NOI17_roadsideadverts)	C++17	100 / 100	134 ms	14956 KiB

roadsideadverts

#include <bits/stdc++.h>

#define FAST_IO ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr)
#define setIO(i, o) freopen(i, "r", stdin), freopen(o, "w", stdout)
#define seed() srand(chrono::steady_clock::now().time_since_epoch().count())
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int) (x).size()
#define lc(i) 2*i
#define rc(i) 2*i+1
//#define int long long
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using vii = vector<ii>;
using vi = vector<int>;
using vvi = vector<vi>;
using vb = vector<bool>;
using vvb = vector<vb>;

ll rng() {
    ll a = rand();
    ll b = rand();
    return a * (RAND_MAX + 1ll) + b;
}

const int N = 5e4 + 5, MOD = 1e9 + 7, INF = 1e9 + 5;
vii g[N];

struct LCA {
    int n, k, timer;
    vector<int> tin, tout;
    vector<vector<pair<int, int>>> par;

    void init(int x) {
        n = x;
        k = 31 - __builtin_clz(n);
        timer = 0;
        tin.resize(n);
        tout.resize(n);
        par.assign(n, vector<pair<int, int>>(k + 1, {0, 0}));
    }

    void dfs(int u = 0, int p = -1, int lastWt = 0) {
        tin[u] = timer++;

        par[u][0].first = (p == -1 ? 0 : p);
        par[u][0].second = lastWt;

        for (int j = 1; j <= k; j++) {
            par[u][j].first = par[par[u][j - 1].first][j - 1].first;
            par[u][j].second = par[u][j - 1].second + par[par[u][j - 1].first][j  - 1].second;
        }

        for (const auto &[v, wt] : g[u]) if (v != p) dfs(v, u, wt);
        tout[u] = timer - 1;
    }

    bool isAnc(int x, int v) {
        return tin[x] <= tin[v] && tout[x] >= tout[v];
    }

    int getLCA(int u, int v) {
        if (isAnc(u, v)) return u;
        if (isAnc(v, u)) return v;
        for (int j = k; j >= 0; j--) if (!isAnc(par[u][j].first, v)) u = par[u][j].first;
        return par[u][0].first;
    }

    int getCost(int u, int v) {
        if (u == v) return 0;

        int ans = 0;

        for (int j = k; j >= 0; j--) {
            if (isAnc(par[u][j].first, v)) continue;
            ans += par[u][j].second;
            u = par[u][j].first;
        }

        return ans + par[u][0].second;
    }
};

void solve() {
    int n;
    cin >> n;

    for (int i = 1; i < n; i++) {
        int u, v, w;
        cin >> u >> v >> w;

        g[u].eb(v, w);
        g[v].eb(u, w);
    }

    LCA binlift;
    binlift.init(n);
    binlift.dfs();

    int q;
    cin >> q;

    while (q--) {
        vi qry(5);
        for (auto &x : qry) cin >> x;

        sort(all(qry), [&](const auto &x, const auto &y) { return binlift.tin[x] < binlift.tin[y]; });

        int root = binlift.getLCA(qry[0], qry[1]);

        for (int i = 2; i < 5; i++)
            root = binlift.getLCA(root, qry[i]);

        int ans = binlift.getCost(qry[0], root);

        for (int i = 1; i < 5; i++) {
            int lca = binlift.getLCA(qry[i - 1], qry[i]);
            ans += binlift.getCost(qry[i], lca);
        }

        cout << ans << "\n";
    }
}

signed main() {
    FAST_IO;
#ifdef arujbansal_local
    setIO("input.txt", "output.txt");
#endif

    seed();

    int tc = 1;
//    cin >> tc;
    while (tc--) solve();
}

• Subtask 1: 7 / 7
• Subtask 2: 23 / 23
• Subtask 3: 40 / 40
• Subtask 4: 30 / 30