Submission #336320

#	Time	Username	Problem	Language	Result	Execution time	Memory
336320		12tqian	Bridges (APIO19_bridges)	C++17	14 / 100	1765 ms	10236 KiB

bridges

#include <bits/stdc++.h>

struct DSU {
    std::vector<int> e;
    void init(int n) {
        e = std::vector<int>(n, -1);
    }
    int get(int x) {
        return e[x] < 0 ? x : e[x] = get(e[x]);
    }
    bool same_set(int a, int b) {
        return get(a) == get(b);
    }
    int size(int x) {
        return -e[get(x)];
    }
    bool unite(int x, int y) {
        x = get(x), y = get(y);
        if (x == y) return false;
        if (e[x] > e[y]) std::swap(x, y);
        e[x] += e[y]; e[y] = x;
        return true;
    }
};

int main() {
    const int B = 800;
    const int INF = 1e9;
    using namespace std;
    ios_base::sync_with_stdio(0);
    int n, m; cin >> n >> m;
    vector<vector<int>> adj(n);
    vector<array<int, 3>> ed;
    vector<int> id(m);
    iota(id.begin(), id.end(), 0);
    for (int i = 0; i < m; i++) {
        int u, v, w; cin >> u >> v >> w;
        u--, v--;
        ed.push_back({u, v, w});
    }
    
    vector<int> mod(m);
    int q; cin >> q;
    vector<array<int, 3>> modify;
    vector<array<int, 3>> queries;
    vector<int> vis(n);
    vector<int> rem;
    vector<array<int, 2>> ans;
    DSU D;
    for (int i = 0; i < q; i++) {
        int x, y, z; cin >> x >> y >> z;
        y--;
        if (x == 1) 
            modify.push_back({y, z, i});
        else 
            queries.push_back({y, z, i});
        if (i == q - 1 || int(modify.size()) + int(queries.size()) == B) {
            sort(id.begin(), id.end(), [&ed](int& x, int & y) {
                return ed[x][2] < ed[y][2];
            }); 
            D.init(n);
            sort(queries.begin(), queries.end(), [](array<int, 3>& a, array<int, 3>& b) {
                return a[1] > b[1];
            });
            for (auto& mm : modify) 
                mod[mm[0]] = 1;
            int it = m;
            for (auto& qq : queries) {
                int weight = qq[1];
                int ti = qq[2];
                while (it && ed[id[it - 1]][2] >= weight) {
                    it--;
                    if (!mod[id[it]]) 
                        D.unite(ed[id[it]][0], ed[id[it]][1]);
                }
                for (auto& mm : modify) { 
                    if (mm[2] > ti || mm[1] >= weight) {
                        int eid = mm[0];
                        int u = D.get(ed[eid][0]);
                        int v = D.get(ed[eid][1]);
                        adj[u].push_back(v);
                        adj[v].push_back(u);
                    } 
                }
                int res = 0;
                function<void(int)> dfs = [&](int src) {
                    res += D.size(src);
                    rem.push_back(src);
                    vis[src] = 1;
                    for (int nxt : adj[src]) {
                        if (vis[nxt])
                            continue;
                        dfs(nxt);
                    }
                };
                dfs(D.get(qq[0]));
                ans.push_back({ti, res});
                for (int r : rem)
                    vis[r] = 0;
                rem.clear();
                for (auto& mm : modify) { 
                    if (mm[2] > ti || mm[1] >= weight) {
                        int eid = mm[0];
                        int u = D.get(ed[eid][0]);
                        int v = D.get(ed[eid][1]);
                        adj[u].pop_back();
                        adj[v].pop_back();
                    }
                }
            }
            for (auto& mm : modify)
                mod[mm[0]] = 0, ed[mm[0]][2] = mm[1];
            queries.clear();
            modify.clear();
        }
    }
    sort(ans.begin(), ans.end());
    for (auto& a : ans) 
        cout << a[1] << '\n';
    return 0;
}

Compilation message (stderr)

bridges.cpp: In function 'int main()':
bridges.cpp:28:15: warning: unused variable 'INF' [-Wunused-variable]
   28 |     const int INF = 1e9;
      |               ^~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 16
• Subtask 3: 0 / 17
• Subtask 4: 14 / 14
• Subtask 5: 0 / 13
• Subtask 6: 0 / 27