Submission #1128673

#	Time	Username	Problem	Language	Result	Execution time	Memory
1128673		_callmelucian	Evacuation plan (IZhO18_plan)	C++17	100 / 100	465 ms	42256 KiB

plan

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pl;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tpl;

#define all(a) a.begin(), a.end()
#define filter(a) a.erase(unique(all(a)), a.end())

const int mn = 1e5 + 5;
vector<pl> adj[mn];
ll dist[mn], n;
bool vis[mn];

void dijkstra (const vector<int> &sources) {
    for (int i = 1; i <= n; i++)
        dist[i] = LLONG_MAX, vis[i] = 0;
    priority_queue<pl> pq;
    for (int u : sources)
        dist[u] = 0, pq.emplace(0, u);

    while (pq.size()) {
        int u = pq.top().second; pq.pop();
        if (vis[u]) continue;
        vis[u] = 1;
        for (pl item : adj[u]) {
            ll v, w; tie(v, w) = item;
            if (dist[u] + w < dist[v]) {
                dist[v] = dist[u] + w;
                pq.emplace(-dist[v], v);
            }
        }
    }
}

namespace tree {
    int spt[mn][17], par[mn], chain[mn], sz[mn], depth[mn], num[mn], timeDfs;
    vector<int> adj[mn];

    int szDfs (int u, int p) {
        sz[u] = 1;
        for (int v : adj[u])
            if (v != p) sz[u] += szDfs(v, u);
        return sz[u];
    }

    void dfs (int u, int p, int d, bool toP) {
        if (u == 1) szDfs(u, p);
        num[u] = ++timeDfs, par[u] = p, depth[u] = d;
        chain[u] = (toP ? chain[p] : u);
        sort(all(adj[u]), [&] (int a, int b) {
                return sz[a] > sz[b];
             });
        bool heavy = 1;
        for (int v : adj[u])
            if (v != p) dfs(v, u, d + 1, heavy), heavy = 0;
    }

    int rmq (int l, int r) {
        int p = 31 - __builtin_clz(r - l + 1);
        return min(spt[l][p], spt[r - (1 << p) + 1][p]);
    }

    int query (int a, int b) {
        int ans = INT_MAX;
        while (chain[a] != chain[b]) {
            int ap = par[chain[a]], bp = par[chain[b]];
            if (depth[ap] == depth[bp]) {
                ans = min(ans, rmq(num[chain[a]], num[a])), a = ap;
                ans = min(ans, rmq(num[chain[b]], num[b])), b = bp;
            }
            else if (depth[ap] > depth[bp])
                ans = min(ans, rmq(num[chain[a]], num[a])), a = ap;
            else if (depth[bp] > depth[ap])
                ans = min(ans, rmq(num[chain[b]], num[b])), b = bp;
        }
        if (depth[a] > depth[b]) swap(a, b);
        return min(ans, rmq(num[a], num[b]));
    }

    void process() {
        dfs(1, 0, 1, 0);
        for (int i = 1; i <= n; i++) spt[num[i]][0] = dist[i];
        for (int s = 1; (1 << s) <= n; s++) {
            for (int i = 1; i + (1 << s) - 1 <= n; i++) {
                int p = s - 1;
                spt[i][s] = min(spt[i][p], spt[i + (1 << p)][p]);
            }
        }
    }

    void addEdge (int a, int b) {
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
};

struct DSU {
    vector<int> lab;
    DSU (int sz) : lab(sz + 1, -1) {}

    int get (int u) {
        if (lab[u] < 0) return u;
        return lab[u] = get(lab[u]);
    }

    bool unite (int a, int b) {
        a = get(a), b = get(b);
        if (a == b) return 0;
        if (-lab[a] < -lab[b]) swap(a, b);
        lab[a] += lab[b], lab[b] = a;
        return 1;
    }
};

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    int m; cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int a, b, c; cin >> a >> b >> c;
        adj[a].emplace_back(b, c);
        adj[b].emplace_back(a, c);
    }

    int k; cin >> k;
    vector<int> sources(k), ord(n);
    for (int &u : sources) cin >> u;
    dijkstra(sources);

    for (int i = 1; i <= n; i++) ord[i - 1] = i;
    sort(all(ord), [&] (int a, int b) { return dist[a] > dist[b]; });

    vector<bool> added(n + 1);
    DSU dsu(n);
    for (int u : ord) {
        added[u] = 1;
        for (pl item : adj[u]) {
            int v = item.first;
            if (added[v] && dsu.unite(u, v)) tree::addEdge(u, v);
        }
    }
    tree::process();

    int q; cin >> q;
    while (q--) {
        int u, v; cin >> u >> v;
        cout << tree::query(u, v) << "\n";
    }

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46