Submission #387711

#	Time	Username	Problem	Language	Result	Execution time	Memory
387711		arujbansal	Factories (JOI14_factories)	C++17	0 / 100	4466 ms	173100 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;

struct LCA {
    int n, k;
    vector<vector<int>> adj, sparse_table;
    vector<int> euler, first_occurrence;
    int timer;
    bool lca_built;

    LCA(int _n = 0) { 
        lca_built = false;

        if (_n > 0)
            init(_n);
    }

    void init(int _n) {
        lca_built = false;

        n = _n;

        adj.resize(n);
        for (int i = 0; i < n; i++)
            adj[i].clear();

        euler.clear();
        first_occurrence.resize(n);
        timer = 0;
    }

    void add_edge(int u, int v) {
        assert(n > 0);

        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    void run(int root = 0) {
        assert(n > 0);

        dfs(root, -1);
        build();

        lca_built = true;
    }

    void dfs(int u = 0, int p = -1) {
        first_occurrence[u] = timer++;
        euler.push_back(u);

        for (const auto &v : adj[u]) {
            if (v == p) continue;
            
            dfs(v, u);
            euler.push_back(u);
            timer++;
        }
    }

    void build() {
        k = 31 - __builtin_clz(timer) + 1;

        sparse_table.resize(k);

        for (int i = 0; i < k; i++)
            sparse_table[i].resize(timer - (1 << i) + 1);

        for (int j = 0; j < timer; j++)
            sparse_table[0][j] = euler[j];

        for (int i = 1; i < k; i++) {
            for (int j = 0; j + (1 << i) - 1 < timer; j++) {
                int x = sparse_table[i - 1][j];
                int y = sparse_table[i - 1][j + (1 << (i - 1))];

                sparse_table[i][j] = (first_occurrence[x] < first_occurrence[y] ? x : y);
            }
        }
    }

    int query(int u, int v) {
        assert(lca_built == true);

        int l = first_occurrence[u], r = first_occurrence[v];
        if (l > r)
            swap(l, r);

        int i = 31 - __builtin_clz(r - l + 1);

        int x = sparse_table[i][l], y = sparse_table[i][r - (1 << i) + 1];
        return first_occurrence[x] < first_occurrence[y] ? x : y;
    }
};

const int MXN = 5e5 + 5, MXK = 19;
const ll INF = 1e18;
vector<pair<int, ll>> g[MXN];
int cd_par[MXN], subtree[MXN];
bool vis[MXN];
ll dist_g[MXN], best[MXN];
LCA lca_g;

void dfs1(int u, int p, int cur_dist) {
    dist_g[u] = cur_dist;

    for (const auto &[v, w] : g[u]) {
        if (v == p) continue;
        dfs1(v, u, cur_dist + w);
    }
}

ll dist(int u, int v) {
    if (u == v) return 0;
    int cur_lca = lca_g.query(u, v);
    return dist_g[u] - dist_g[cur_lca] + dist_g[v] - dist_g[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[]) {
    lca_g.init(N);

    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]);

        lca_g.add_edge(A[i], B[i]);
    }

    lca_g.run(0);

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

    for (int i = 0; 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