Submission #1198749

#	Time	Username	Problem	Language	Result	Execution time	Memory
1198749		alenhsiao	Bridges (APIO19_bridges)	C++20	0 / 100	87 ms	10396 KiB

bridges

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

const int MAXN = 5e4 + 5;
const int MAXQ = 1e5 + 5;

struct Edge {
    int u, v, w, id;
};

struct Query {
    int type; // 1=update, 2=query
    int t, a, b, idx; // for query: a=s, b=w
};

int parent[MAXN], sz[MAXN];
int bridge_weight[MAXQ], final_weight[MAXQ];
vector<Edge> edges;
vector<Query> queries;

int find(int x) {
    return parent[x] == x ? x : parent[x] = find(parent[x]);
}

void unite(int x, int y) {
    x = find(x); y = find(y);
    if (x != y) {
        if (sz[x] < sz[y]) swap(x, y);
        parent[y] = x;
        sz[x] += sz[y];
    }
}

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

    int n, m; cin >> n >> m;
    edges.resize(m);

    for (int i = 0; i < m; ++i) {
        int u, v, d;
        cin >> u >> v >> d;
        edges[i] = {u, v, d, i};
        bridge_weight[i] = d;
        final_weight[i] = d;
    }

    int q; cin >> q;
    vector<pair<int, int>> mod(m, {-1, -1}); // 最後限重紀錄

    vector<pair<int, pair<int, int>>> off; // {weight, {type, idx}}: type=0=edge, type=1=query
    vector<int> ans;

    for (int i = 0; i < q; ++i) {
        int t; cin >> t;
        if (t == 1) {
            int id, new_w;
            cin >> id >> new_w; --id;
            final_weight[id] = new_w;
        } else {
            int s, w;
            cin >> s >> w;
            queries.push_back({2, i, s, w, (int)ans.size()});
            ans.push_back(0);
        }
    }

    // 將 edge 和 query 合併一起排序（權重大到小）
    vector<pair<int, int>> event;
    for (int i = 0; i < m; ++i)
        event.push_back({final_weight[i], ~i}); // edge id as ~i
    for (int i = 0; i < (int)queries.size(); ++i)
        event.push_back({queries[i].b, i}); // query index

    sort(event.rbegin(), event.rend());

    iota(parent, parent + n + 1, 0);
    fill(sz, sz + n + 1, 1);

    vector<bool> used(m, false);

    for (auto [w, id] : event) {
        if (id < 0) {
            int eid = ~id;
            if (used[eid]) continue;
            unite(edges[eid].u, edges[eid].v);
            used[eid] = true;
        } else {
            int root = find(queries[id].a);
            ans[queries[id].idx] = sz[root];
        }
    }

    for (int x : ans)
        cout << x << '\n';

    return 0;
}

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