Submission #387691

#	Time	Username	Problem	Language	Result	Execution time	Memory
387691		arujbansal	Factories (JOI14_factories)	C++17	0 / 100	3424 ms	21708 KiB

factories

#include "factories.h"

#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <array>
#include <stack>
#include <queue>
#include <random>
#include <numeric>
#include <functional>
#include <chrono>
#include <utility>
#include <iomanip>
#include <assert.h>

using namespace std;

void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail>
void dbg_out(Head H, Tail... T) { cerr << ' ' << H; dbg_out(T...); }
#define dbg(...) cerr << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)

#define rng_init mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define rng_seed(x) mt19937 rng(x)
#define all(x) (x).begin(), (x).end()
#define sz(x) (int) (x).size()
// #define int long long

using ll = long long;

const int MXN = 5e5 + 5, MXK = 20;
const ll INF = 1e18;
vector<pair<int, ll>> g[MXN];
int cd_par[MXN], binlift_par[MXN][MXK], tin[MXN], tout[MXN], subtree[MXN];
ll binlift_dist[MXN][MXK], best[MXN];
bool vis[MXN];
int timer;

void dfs1(int u, int p) {
    tin[u] = timer++;

    for (int j = 1; j < MXK; j++) {
        binlift_par[u][j] = binlift_par[binlift_par[u][j - 1]][j - 1];
        binlift_dist[u][j] = binlift_dist[u][j - 1] + binlift_dist[binlift_par[u][j - 1]][j - 1];
    }

    for (const auto &[v, w] : g[u]) {
        if (v == p) continue;

        binlift_par[v][0] = u;
        binlift_dist[v][0] = w;

        dfs1(v, u);
    }

    tout[u] = timer - 1;
}

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

int query_lca(int u, int v) {
    if (is_anc(u, v)) return u;
    if (is_anc(v, u)) return v;

    for (int j = MXK - 1; j >= 0; j--) {
        int lift = binlift_par[u][j];

        if (!is_anc(lift, v))
            u = lift;
    }

    return binlift_par[u][0];
}

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

    ll res = 0;

    for (int j = MXK - 1; j >= 0; j--) {
        int lift = binlift_par[u][j];

        if (!is_anc(lift, v)) {
            res += binlift_dist[u][j];
            u = lift;
        }
    }

    return res + binlift_dist[u][0];
}

ll dist(int u, int v) {
    if (u == v) return 0;
    int cur_lca = query_lca(u, v);
    return query_dist(u, cur_lca) + query_dist(v, cur_lca);
}

void dfs_subtree(int u, int p) {
    subtree[u] = 1;

    for (const auto &[v, w] : g[u]) {
        if (v == p || vis[v]) continue;

        dfs_subtree(v, u);
        subtree[u] += subtree[v];
    }
}

int centroid(int u, int p, int vertices) {
    for (const auto &[v, w] : g[u]) {
        if (v == p || vis[v]) continue;

        if (subtree[v] * 2 > vertices)
            return centroid(v, u, vertices);
    }

    return u;
}

void build_cd(int u, int p) {
    dfs_subtree(u, -1);
    int c = centroid(u, -1, subtree[u]);

    if (p == -1)
        p = c;

    cd_par[c] = p;
    vis[c] = true;

    for (const auto &[v, w] : g[c]) {
        if (vis[v]) continue;
        build_cd(v, c);
    }
}

void build_factory(int u) {
    int v = u;
    best[v] = 0;

    do {
        v = cd_par[v];
        best[v] = min(best[v], dist(u, v));
    } while (v != cd_par[v]);
}

void remove_factory(int v) {
    best[v] = INF;

    do {
        v = cd_par[v];
        best[v] = INF;
    } while (v != cd_par[v]);
}

ll query_factory(int u) {
    int v = u;
    ll ans = best[v];

    do {
        v = cd_par[v];
        ans = min(ans, dist(u, v) + best[v]);
    } while (v != cd_par[v]);

    return ans;
}

void Init(int N, int A[], int B[], int D[]) {
    for (int i = 0; i < N - 1; i++) {
        g[A[i]].emplace_back(B[i], D[i]);
        g[B[i]].emplace_back(A[i], D[i]);
    }

    dfs1(0, -1);
    build_cd(0, -1);

    for (int i = 1; i <= N; i++)
        best[i] = INF;
}

ll Query(int S, int X[], int T, int Y[]) {
    ll ans = INF;

    for (int i = 0; i < S; i++)
        build_factory(X[i]);

    for (int i = 0; i < T; i++)
        ans = min(ans, query_factory(Y[i]));

    for (int i = 0; i < S; i++)
        remove_factory(X[i]);

    return ans;
}

// void solve() {
//     int N,  Q;
//     cin >> N >> Q;

//     int A[N - 1], B[N - 1], D[N - 1];
//     for (int i = 0; i < N - 1; i++)
//         cin >> A[i] >> B[i] >> D[i];

//     Init(N, A, B, D);

//     while (Q--) {
//         int S, T;
//         cin >> S >> T;

//         int X[S], Y[T];
//         for (int i = 0; i < S; i++)
//             cin >> X[i];

//         for (int i = 0; i < T; i++)
//             cin >> Y[i];

//         cout << Query(S, X, T, Y) << "\n";
//     }
// }

// signed main() {
//     ios_base::sync_with_stdio(false);
//     cin.tie(nullptr);

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

• Subtask 1: 0 / 15
• Subtask 2: 0 / 18
• Subtask 3: 0 / 67